diff --git a/.cirrus.yml b/.cirrus.yml
index d4aedd3955..e7688d22c5 100644
--- a/.cirrus.yml
+++ b/.cirrus.yml
@@ -1,5 +1,6 @@
 # Reference:
 #   - https://cirrus-ci.org/guide/writing-tasks/
+#   - https://cirrus-ci.org/guide/writing-tasks/#environment-variables
 #   - https://cirrus-ci.org/guide/tips-and-tricks/#sharing-configuration-between-tasks
 #   - https://cirrus-ci.org/guide/linux/
 #   - https://cirrus-ci.org/guide/macOS/
@@ -17,6 +18,16 @@ container:
 
 
 env:
+  # Skip specific tasks by name. Set to a non-empty string to skip.
+  SKIP_LINT_TASK: ""
+  SKIP_TEST_MINIMAL_TASK: ""
+  SKIP_TEST_FULL_TASK: ""
+  SKIP_GALLERY_TASK: ""
+  SKIP_DOCTEST_TASK: ""
+  SKIP_LINKCHECK_TASK: ""
+  # Skip task groups by type. Set to a non-empty string to skip.
+  SKIP_ALL_TEST_TASKS: ""
+  SKIP_ALL_DOC_TASKS: ""
   # Maximum cache period (in weeks) before forcing a new cache upload.
   CACHE_PERIOD: "2"
   # Increment the build number to force new cartopy cache upload.
@@ -35,25 +46,6 @@ env:
   IRIS_TEST_DATA_DIR: ${HOME}/iris-test-data
 
 
-#
-# Linting
-#
-lint_task:
-  auto_cancellation: true
-  name: "${CIRRUS_OS}: flake8 and black"
-  pip_cache:
-    folder: ~/.cache/pip
-    fingerprint_script:
-      - echo "${CIRRUS_TASK_NAME}"
-      - echo "$(date +%Y).$(($(date +%U) / ${CACHE_PERIOD})):${PIP_CACHE_BUILD} ${PIP_CACHE_PACKAGES}"
-  lint_script:
-    - pip list
-    - python -m pip install --retries 3 --upgrade ${PIP_CACHE_PACKAGES}
-    - pip list
-    - nox --session flake8
-    - nox --session black
-
-
 #
 # YAML alias for common linux test infra-structure.
 #
@@ -68,7 +60,7 @@ linux_task_template: &LINUX_TASK_TEMPLATE
     fingerprint_script:
       - wget --quiet https://repo.continuum.io/miniconda/Miniconda3-latest-Linux-x86_64.sh -O miniconda.sh
       - echo "${CIRRUS_OS} $(sha256sum miniconda.sh)"
-      - echo "$(date +%Y).$(($(date +%U) / ${CACHE_PERIOD})):${CONDA_CACHE_BUILD}"
+      - echo "$(date +%Y).$(expr $(date +%U) / ${CACHE_PERIOD}):${CONDA_CACHE_BUILD}"
     populate_script:
       - bash miniconda.sh -b -p ${HOME}/miniconda
       - conda config --set always_yes yes --set changeps1 no
@@ -80,19 +72,49 @@ linux_task_template: &LINUX_TASK_TEMPLATE
     folder: ${HOME}/.local/share/cartopy
     fingerprint_script:
       - echo "${CIRRUS_OS}"
-      - echo "$(date +%Y).$(($(date +%U) / ${CACHE_PERIOD})):${CARTOPY_CACHE_BUILD}"
+      - echo "$(date +%Y).$(expr $(date +%U) / ${CACHE_PERIOD}):${CARTOPY_CACHE_BUILD}"
   nox_cache:
     folder: ${CIRRUS_WORKING_DIR}/.nox
     fingerprint_script:
       - echo "${CIRRUS_TASK_NAME}"
-      - echo "$(date +%Y).$(($(date +%U) / ${CACHE_PERIOD})):${NOX_CACHE_BUILD}"
+      - echo "$(date +%Y).$(expr $(date +%U) / ${CACHE_PERIOD}):${NOX_CACHE_BUILD}"
       - sha256sum ${CIRRUS_WORKING_DIR}/requirements/ci/py$(echo ${PY_VER} | tr -d ".").yml
 
 
+#
+# YAML alias for compute credits
+#
+compute_credits_template: &CREDITS_TEMPLATE
+  # Only use credits for non-DRAFT pull-requests to SciTools/iris master branch by collaborators
+  use_compute_credits: $CIRRUS_REPO_FULL_NAME == 'SciTools/iris' && $CIRRUS_USER_COLLABORATOR == 'true' && $CIRRUS_PR_DRAFT == 'false' && $CIRRUS_BASE_BRANCH == 'master' && $CIRRUS_PR != ''
+
+#
+# Linting
+#
+lint_task:
+  only_if: $SKIP_LINT_TASK == ""
+  << : *CREDITS_TEMPLATE
+  auto_cancellation: true
+  name: "${CIRRUS_OS}: flake8 and black"
+  pip_cache:
+    folder: ~/.cache/pip
+    fingerprint_script:
+      - echo "${CIRRUS_TASK_NAME}"
+      - echo "$(date +%Y).$(expr $(date +%U) / ${CACHE_PERIOD}):${PIP_CACHE_BUILD} ${PIP_CACHE_PACKAGES}"
+  lint_script:
+    - pip list
+    - python -m pip install --retries 3 --upgrade ${PIP_CACHE_PACKAGES}
+    - pip list
+    - nox --session flake8
+    - nox --session black
+
+
 #
 # Testing Minimal (Linux)
 #
-linux_minimal_task:
+test_minimal_task:
+  only_if: $SKIP_TEST_MINIMAL_TASK == "" && $SKIP_ALL_TEST_TASKS == ""
+  << : *CREDITS_TEMPLATE
   matrix:
     env:
       PY_VER: 3.6
@@ -113,7 +135,9 @@ linux_minimal_task:
 #
 # Testing Full (Linux)
 #
-linux_task:
+test_full_task:
+  only_if: $SKIP_TEST_FULL_TASK == "" && $SKIP_ALL_TEST_TASKS == ""
+  << : *CREDITS_TEMPLATE
   matrix:
     env:
       PY_VER: 3.6
@@ -144,6 +168,8 @@ linux_task:
 # Testing Documentation Gallery (Linux)
 #
 gallery_task:
+  only_if: $SKIP_GALLERY_TASK == "" && $SKIP_ALL_DOC_TASKS == ""
+  << : *CREDITS_TEMPLATE
   matrix:
     env:
       PY_VER: 3.6
@@ -174,6 +200,8 @@ gallery_task:
 # Testing Documentation (Linux)
 #
 doctest_task:
+  only_if: $SKIP_DOCTEST_TASK == "" && $SKIP_ALL_DOC_TASKS == ""
+  << : *CREDITS_TEMPLATE
   matrix:
     env:
       PY_VER: 3.7
@@ -207,7 +235,9 @@ doctest_task:
 #
 # Testing Documentation Link Check (Linux)
 #
-link_task:
+linkcheck_task:
+  only_if: $SKIP_LINKCHECK_TASK == "" && $SKIP_ALL_DOC_TASKS == ""
+  << : *CREDITS_TEMPLATE
   matrix:
     env:
       PY_VER: 3.7
diff --git a/docs/iris/gallery_code/general/plot_anomaly_log_colouring.py b/docs/iris/gallery_code/general/plot_anomaly_log_colouring.py
index 778f92db1b..846816aff7 100644
--- a/docs/iris/gallery_code/general/plot_anomaly_log_colouring.py
+++ b/docs/iris/gallery_code/general/plot_anomaly_log_colouring.py
@@ -12,18 +12,15 @@
 "zero band" which is plotted in white.
 
 To do this, we create a custom value mapping function (normalization) using
-the matplotlib Norm class `matplotlib.colours.SymLogNorm
-<https://matplotlib.org/api/_as_gen/matplotlib.colors.SymLogNorm.html#matplotlib.colors.SymLogNorm>`_.
-We use this to make a cell-filled pseudocolour plot with a colorbar.
+the matplotlib Norm class :obj:`matplotlib.colors.SymLogNorm`.
+We use this to make a cell-filled pseudocolor plot with a colorbar.
 
 NOTE: By "pseudocolour", we mean that each data point is drawn as a "cell"
 region on the plot, coloured according to its data value.
 This is provided in Iris by the functions :meth:`iris.plot.pcolor` and
 :meth:`iris.plot.pcolormesh`, which call the underlying matplotlib
-functions of the same names (i.e. `matplotlib.pyplot.pcolor
-<http://matplotlib.org/api/pyplot_api.html#matplotlib.pyplot.pcolor>`_
-and  `matplotlib.pyplot.pcolormesh
-<http://matplotlib.org/api/pyplot_api.html#matplotlib.pyplot.pcolormesh>`_).
+functions of the same names (i.e., :obj:`matplotlib.pyplot.pcolor`
+and :obj:`matplotlib.pyplot.pcolormesh`).
 See also: http://en.wikipedia.org/wiki/False_color#Pseudocolor.
 
 """
@@ -65,7 +62,7 @@ def main():
 
     # Use a standard colour map which varies blue-white-red.
     # For suitable options, see the 'Diverging colormaps' section in:
-    # http://matplotlib.org/examples/color/colormaps_reference.html
+    # http://matplotlib.org/stable/gallery/color/colormap_reference.html
     anom_cmap = "bwr"
 
     # Create a 'logarithmic' data normalization.
diff --git a/docs/iris/src/common_links.inc b/docs/iris/src/common_links.inc
index 3941bfaff2..1b11fcc16b 100644
--- a/docs/iris/src/common_links.inc
+++ b/docs/iris/src/common_links.inc
@@ -1,9 +1,11 @@
 .. _SciTools: https://github.com/SciTools
+.. _black: https://black.readthedocs.io/en/stable/
 .. _Iris: https://github.com/SciTools/iris
 .. _Iris GitHub: https://github.com/SciTools/iris
 .. _iris mailing list: https://groups.google.com/forum/#!forum/scitools-iris
 .. _issue: https://github.com/SciTools/iris/issues
 .. _issues: https://github.com/SciTools/iris/issues
+.. _matplotlib: https://matplotlib.org/stable/
 .. _pull request: https://github.com/SciTools/iris/pulls
 .. _pull requests: https://github.com/SciTools/iris/pulls
 .. _contributor: https://github.com/SciTools/scitools.org.uk/blob/master/contributors.json
@@ -14,14 +16,13 @@
 .. _readthedocs.yml: https://github.com/SciTools/iris/blob/master/requirements/ci/readthedocs.yml
 .. _cirrus-ci: https://cirrus-ci.com/github/SciTools/iris
 .. _.cirrus.yml: https://github.com/SciTools/iris/blob/master/.cirrus.yml
+.. _flake8: https://flake8.pycqa.org/en/stable/
 .. _.flake8.yml: https://github.com/SciTools/iris/blob/master/.flake8
 .. _GitHub Help Documentation: https://docs.github.com/en/github
 .. _using git: https://docs.github.com/en/github/using-git
 .. _generating sss keys for GitHub: https://docs.github.com/en/github/authenticating-to-github/adding-a-new-ssh-key-to-your-github-account
 .. _New Issue: https://github.com/scitools/iris/issues/new/choose
-.. _matplotlib: https://matplotlib.org/
 .. _conda: https://docs.conda.io/en/latest/
 .. _sphinx: https://www.sphinx-doc.org/en/master/
 .. _napolean: https://sphinxcontrib-napoleon.readthedocs.io/en/latest/sphinxcontrib.napoleon.html
 .. _legacy documentation: https://scitools.org.uk/iris/docs/v2.4.0/
-.. _cirrus-ci: https://cirrus-ci.com/github/SciTools/iris
diff --git a/docs/iris/src/conf.py b/docs/iris/src/conf.py
index 8be849b7ce..09494d5d00 100644
--- a/docs/iris/src/conf.py
+++ b/docs/iris/src/conf.py
@@ -179,18 +179,18 @@ def autolog(message):
 # -- intersphinx extension ----------------------------------------------------
 # See https://www.sphinx-doc.org/en/master/usage/extensions/intersphinx.html
 intersphinx_mapping = {
-    "cartopy": ("http://scitools.org.uk/cartopy/docs/latest/", None),
-    "matplotlib": ("http://matplotlib.org/", None),
-    "numpy": ("http://docs.scipy.org/doc/numpy/", None),
-    "python": ("http://docs.python.org/2.7", None),
-    "scipy": ("http://docs.scipy.org/doc/scipy/reference/", None),
+    "cartopy": ("https://scitools.org.uk/cartopy/docs/latest/", None),
+    "matplotlib": ("https://matplotlib.org/stable/", None),
+    "numpy": ("https://numpy.org/doc/stable/", None),
+    "python": ("https://docs.python.org/3/", None),
+    "scipy": ("https://docs.scipy.org/doc/scipy/reference/", None),
 }
 
 # The name of the Pygments (syntax highlighting) style to use.
 pygments_style = "sphinx"
 
 # -- plot_directive extension -------------------------------------------------
-# See https://matplotlib.org/3.1.3/devel/plot_directive.html#options
+# See https://matplotlib.org/stable/api/sphinxext_plot_directive_api.html#options
 plot_formats = [
     ("png", 100),
 ]
diff --git a/docs/iris/src/developers_guide/contributing_ci_tests.rst b/docs/iris/src/developers_guide/contributing_ci_tests.rst
index a6bdac4ae0..8594612fe1 100644
--- a/docs/iris/src/developers_guide/contributing_ci_tests.rst
+++ b/docs/iris/src/developers_guide/contributing_ci_tests.rst
@@ -5,9 +5,9 @@
 Continuous Integration (CI) Testing
 ===================================
 
-The `Iris`_ GitHub repository is configured to run checks on the code
-automatically when a pull request is created, updated or merged against
-Iris **master**.  The checks performed are:
+The `Iris`_ GitHub repository is configured to run checks against all its
+branches automatically whenever a pull request is created, updated or merged.
+The checks performed are:
 
 * :ref:`testing_cla`
 * :ref:`testing_cirrus`
@@ -18,9 +18,9 @@ Iris **master**.  The checks performed are:
 SciTools CLA Checker
 ********************
 
-A bot that checks the user who created the pull request has signed the
-**Contributor's License Agreement (CLA)**.  For more information on this this
-please see https://scitools.org.uk/organisation.html#governance
+A bot which checks that the GitHub author of the pull request has signed the
+**SciTools Contributor's License Agreement (CLA)**.  For more information on
+this please see https://scitools.org.uk/organisation.html#governance.
 
 
 .. _testing_cirrus:
@@ -28,19 +28,55 @@ please see https://scitools.org.uk/organisation.html#governance
 Cirrus-CI
 *********
 
-The unit and integration tests in Iris are an essential mechanism to ensure
+Iris unit and integration tests are an essential mechanism to ensure
 that the Iris code base is working as expected.  :ref:`developer_running_tests`
-may be run manually but to ensure the checks are performed a
-continuous integration testing tool named `cirrus-ci`_ is used.
+may be performed manually by a developer locally. However Iris is configured to
+use the `cirrus-ci`_ service for automated Continuous Integration (CI) testing.
 
-A `cirrus-ci`_ configuration file named `.cirrus.yml`_
-is in the Iris repository which tells Cirrus-CI what commands to run.  The
-commands include retrieving the Iris code base and associated test files using
-conda and then running the tests.  `cirrus-ci`_ allows for a matrix of tests to
-be performed to ensure that all expected variations test successfully.
+The `cirrus-ci`_ configuration file  `.cirrus.yml`_ in the root of the Iris repository
+defines the tasks to be performed by `cirrus-ci`_. For further details
+refer to the `Cirrus-CI Documentation`_. The tasks performed during CI include:
+
+* linting the code base and ensuring it adheres to the `black`_ format
+* running the system, integration and unit tests for Iris
+* ensuring the documentation gallery builds successfully
+* performing all doc-tests within the code base
+* checking all URL references within the code base and documentation are valid
+
+The above `cirrus-ci`_ tasks are run automatically against all `Iris`_ branches
+on GitHub whenever a pull request is submitted, updated or merged. See the
+`Cirrus-CI Dashboard`_ for details of recent past and active Iris jobs.
+
+.. _skipping Cirrus-CI tasks:
+
+Skipping Cirrus-CI Tasks
+------------------------
+
+As a developer you may wish to not run all the CI tasks when you are actively
+developing e.g., you are writing documentation and there is no need for linting,
+or long running compute intensive testing tasks to be executed.
+
+As a convenience, it is possible to easily skip one or more tasks by setting
+the appropriate environment variable within the `.cirrus.yml`_ file to a
+**non-empty** string:
+
+* ``SKIP_LINT_TASK`` to skip `flake8`_ linting and `black`_ formatting
+* ``SKIP_TEST_MINIMAL_TASK`` to skip restricted unit and integration testing
+* ``SKIP_TEST_FULL_TASK`` to skip full unit and integration testing
+* ``SKIP_GALLERY_TASK`` to skip building the documentation gallery
+* ``SKIP_DOCTEST_TASK`` to skip running the documentation doc-tests
+* ``SKIP_LINKCHECK_TASK`` to skip checking for broken documentation URL references
+* ``SKIP_ALL_TEST_TASKS`` which is equivalent to setting ``SKIP_TEST_MINIMAL_TASK`` and ``SKIP_TEST_FULL_TASK``
+* ``SKIP_ALL_DOC_TASKS`` which is equivalent to setting ``SKIP_GALLERY_TASK``, ``SKIP_DOCTEST_TASK``, and ``SKIP_LINKCHECK_TASK``
+
+e.g., to skip the linting task, the following are all equivalent::
+
+   SKIP_LINT_TASK: "1"
+   SKIP_LINT_TASK: "true"
+   SKIP_LINT_TASK: "false"
+   SKIP_LINT_TASK: "skip"
+   SKIP_LINT_TASK: "unicorn"
 
-The `cirrus-ci`_ tests are run automatically against the `Iris`_ master
-repository when a pull request is submitted, updated or merged.
 
 GitHub Checklist
 ****************
@@ -50,6 +86,10 @@ passing:
 
 .. image:: ci_checks.png
 
-If any CI checks fail, then the pull request is unlikely to be merged to the
+If any CI tasks fail, then the pull request is unlikely to be merged to the
 Iris target branch by a core developer.
 
+
+.. _Cirrus-CI Dashboard: https://cirrus-ci.com/github/SciTools/iris
+.. _Cirrus-CI Documentation: https://cirrus-ci.org/guide/writing-tasks/
+
diff --git a/docs/iris/src/developers_guide/contributing_code_formatting.rst b/docs/iris/src/developers_guide/contributing_code_formatting.rst
index 6bf8dca717..1a3573d135 100644
--- a/docs/iris/src/developers_guide/contributing_code_formatting.rst
+++ b/docs/iris/src/developers_guide/contributing_code_formatting.rst
@@ -58,6 +58,4 @@ will look similar to::
           their officially documentation for more information.
 
 
-.. _black: https://black.readthedocs.io/en/stable/
-.. _flake8: https://flake8.pycqa.org/en/stable/
 .. _pre-commit: https://pre-commit.com/
diff --git a/docs/iris/src/whatsnew/3.0.1.rst b/docs/iris/src/whatsnew/3.0.1.rst
index 597e235ebe..11ad75d95c 100644
--- a/docs/iris/src/whatsnew/3.0.1.rst
+++ b/docs/iris/src/whatsnew/3.0.1.rst
@@ -18,18 +18,17 @@ This document explains the changes made to Iris for this release
 
    💼 **Internal**
 
-   * `@bjlittle`_ gracefully promote formula terms within :mod:`~iris.aux_factory` that have ``units`` of ``unknown``
-     to ``units`` of ``1`` (dimensionless), where the formula term **must** have dimensionless ``units``. Without this
-     graceful treatment of ``units`` the resulting :class:`~iris.cube.Cube` will **not** contain the expected auxiliary
-     factory, and the associated derived coordinate will be missing. (:pull:`3965`)
+   #. `@bjlittle`_ gracefully promote formula terms within :mod:`~iris.aux_factory` that have ``units`` of ``unknown``
+      to ``units`` of ``1`` (dimensionless), where the formula term **must** have dimensionless ``units``. Without this
+      graceful treatment of ``units`` the resulting :class:`~iris.cube.Cube` will **not** contain the expected auxiliary
+      factory, and the associated derived coordinate will be missing. (:pull:`3965`)
 
 
-.. dropdown:: :opticon:`report` Release Highlights
+.. dropdown:: :opticon:`report` v3.0.0 Release Highlights
    :container: + shadow
    :title: text-primary text-center font-weight-bold
    :body: bg-light
    :animate: fade-in
-   :open:
 
    The highlights for this major release of Iris include:
 
@@ -60,204 +59,204 @@ This document explains the changes made to Iris for this release
 📢 Announcements
 ================
 
-* Congratulations to `@bouweandela`_, `@jvegasbsc`_, and `@zklaus`_ who
-  recently became Iris core developers. They bring a wealth of expertise to the
-  team, and are using Iris to underpin `ESMValTool`_ - "*A community diagnostic
-  and performance metrics tool for routine evaluation of Earth system models
-  in CMIP*". Welcome aboard! 🎉
+#. Congratulations to `@bouweandela`_, `@jvegasbsc`_, and `@zklaus`_ who
+   recently became Iris core developers. They bring a wealth of expertise to the
+   team, and are using Iris to underpin `ESMValTool`_ - "*A community diagnostic
+   and performance metrics tool for routine evaluation of Earth system models
+   in CMIP*". Welcome aboard! 🎉
 
-* Congratulations also goes to `@jonseddon`_ who recently became an Iris core
-  developer. We look forward to seeing more of your awesome contributions! 🎉
+#. Congratulations also goes to `@jonseddon`_ who recently became an Iris core
+   developer. We look forward to seeing more of your awesome contributions! 🎉
 
 
 ✨ Features
 ===========
 
-* `@MoseleyS`_ greatly enhanced  the :mod:`~iris.fileformats.nimrod`
-  module to provide richer meta-data translation when loading ``Nimrod`` data
-  into cubes. This covers most known operational use-cases. (:pull:`3647`)
-
-* `@stephenworsley`_ improved the handling of
-  :class:`iris.coords.CellMeasure`\ s in the :class:`~iris.cube.Cube`
-  statistical operations :meth:`~iris.cube.Cube.collapsed`,
-  :meth:`~iris.cube.Cube.aggregated_by` and
-  :meth:`~iris.cube.Cube.rolling_window`. These previously removed every
-  :class:`~iris.coords.CellMeasure` attached to the cube.  Now, a
-  :class:`~iris.coords.CellMeasure` will only be removed if it is associated
-  with an axis over which the statistic is being run. (:pull:`3549`)
-
-* `@stephenworsley`_, `@pp-mo`_ and `@abooton`_ added support for
-  `CF Ancillary Data`_ variables.  These are created as
-  :class:`iris.coords.AncillaryVariable`, and appear as components of cubes
-  much like :class:`~iris.coords.AuxCoord`\ s, with the new
-  :class:`~iris.cube.Cube` methods
-  :meth:`~iris.cube.Cube.add_ancillary_variable`,
-  :meth:`~iris.cube.Cube.remove_ancillary_variable`,
-  :meth:`~iris.cube.Cube.ancillary_variable`,
-  :meth:`~iris.cube.Cube.ancillary_variables` and
-  :meth:`~iris.cube.Cube.ancillary_variable_dims`.
-  They are loaded from and saved to NetCDF-CF files.  Special support for
-  `Quality Flags`_ is also provided, to ensure they load and save with
-  appropriate units. (:pull:`3800`)
-
-* `@bouweandela`_ implemented lazy regridding for the
-  :class:`~iris.analysis.Linear`, :class:`~iris.analysis.Nearest`, and
-  :class:`~iris.analysis.AreaWeighted` regridding schemes. (:pull:`3701`)
-
-* `@bjlittle`_ added `logging`_ support within :mod:`iris.analysis.maths`,
-  :mod:`iris.common.metadata`, and :mod:`iris.common.resolve`. Each module
-  defines a :class:`logging.Logger` instance called ``logger`` with a default
-  ``level`` of ``INFO``. To enable ``DEBUG`` logging use
-  ``logger.setLevel("DEBUG")``. (:pull:`3785`)
-
-* `@bjlittle`_ added the :mod:`iris.common.resolve` module, which provides
-  infrastructure to support the analysis, identification and combination
-  of metadata common between two :class:`~iris.cube.Cube` operands into a
-  single resultant :class:`~iris.cube.Cube` that will be auto-transposed,
-  and with the appropriate broadcast shape. (:pull:`3785`)
-
-* `@bjlittle`_ added the :ref:`common metadata API <metadata>`, which provides
-  a unified treatment of metadata across Iris, and allows users to easily
-  manage and manipulate their metadata in a consistent way. (:pull:`3785`)
-
-* `@bjlittle`_ added :ref:`lenient metadata <lenient metadata>` support, to
-  allow users to control **strict** or **lenient** metadata equivalence,
-  difference and combination. (:pull:`3785`)
-
-* `@bjlittle`_ added :ref:`lenient cube maths <lenient maths>` support and
-  resolved several long standing major issues with cube arithmetic regarding
-  a more robust treatment of cube broadcasting, cube dimension auto-transposition,
-  and preservation of common metadata and coordinates during cube math operations.
-  Resolves :issue:`1887`, :issue:`2765`, and :issue:`3478`. (:pull:`3785`)
-
-* `@pp-mo`_ and `@TomekTrzeciak`_ enhanced :meth:`~iris.cube.Cube.collapse` to allow a 1-D weights array when
-  collapsing over a single dimension.
-  Previously, the weights had to be the same shape as the whole cube, which could cost a lot of memory in some cases.
-  The 1-D form is supported by most weighted array statistics (such as :meth:`np.average`), so this now works
-  with the corresponding Iris schemes (in that case, :const:`~iris.analysis.MEAN`).  (:pull:`3943`)
+#. `@MoseleyS`_ greatly enhanced  the :mod:`~iris.fileformats.nimrod`
+   module to provide richer meta-data translation when loading ``Nimrod`` data
+   into cubes. This covers most known operational use-cases. (:pull:`3647`)
+
+#. `@stephenworsley`_ improved the handling of
+   :class:`iris.coords.CellMeasure`\ s in the :class:`~iris.cube.Cube`
+   statistical operations :meth:`~iris.cube.Cube.collapsed`,
+   :meth:`~iris.cube.Cube.aggregated_by` and
+   :meth:`~iris.cube.Cube.rolling_window`. These previously removed every
+   :class:`~iris.coords.CellMeasure` attached to the cube.  Now, a
+   :class:`~iris.coords.CellMeasure` will only be removed if it is associated
+   with an axis over which the statistic is being run. (:pull:`3549`)
+
+#. `@stephenworsley`_, `@pp-mo`_ and `@abooton`_ added support for
+   `CF Ancillary Data`_ variables.  These are created as
+   :class:`iris.coords.AncillaryVariable`, and appear as components of cubes
+   much like :class:`~iris.coords.AuxCoord`\ s, with the new
+   :class:`~iris.cube.Cube` methods
+   :meth:`~iris.cube.Cube.add_ancillary_variable`,
+   :meth:`~iris.cube.Cube.remove_ancillary_variable`,
+   :meth:`~iris.cube.Cube.ancillary_variable`,
+   :meth:`~iris.cube.Cube.ancillary_variables` and
+   :meth:`~iris.cube.Cube.ancillary_variable_dims`.
+   They are loaded from and saved to NetCDF-CF files.  Special support for
+   `Quality Flags`_ is also provided, to ensure they load and save with
+   appropriate units. (:pull:`3800`)
+
+#. `@bouweandela`_ implemented lazy regridding for the
+   :class:`~iris.analysis.Linear`, :class:`~iris.analysis.Nearest`, and
+   :class:`~iris.analysis.AreaWeighted` regridding schemes. (:pull:`3701`)
+
+#. `@bjlittle`_ added `logging`_ support within :mod:`iris.analysis.maths`,
+   :mod:`iris.common.metadata`, and :mod:`iris.common.resolve`. Each module
+   defines a :class:`logging.Logger` instance called ``logger`` with a default
+   ``level`` of ``INFO``. To enable ``DEBUG`` logging use
+   ``logger.setLevel("DEBUG")``. (:pull:`3785`)
+
+#. `@bjlittle`_ added the :mod:`iris.common.resolve` module, which provides
+   infrastructure to support the analysis, identification and combination
+   of metadata common between two :class:`~iris.cube.Cube` operands into a
+   single resultant :class:`~iris.cube.Cube` that will be auto-transposed,
+   and with the appropriate broadcast shape. (:pull:`3785`)
+
+#. `@bjlittle`_ added the :ref:`common metadata API <metadata>`, which provides
+   a unified treatment of metadata across Iris, and allows users to easily
+   manage and manipulate their metadata in a consistent way. (:pull:`3785`)
+
+#. `@bjlittle`_ added :ref:`lenient metadata <lenient metadata>` support, to
+   allow users to control **strict** or **lenient** metadata equivalence,
+   difference and combination. (:pull:`3785`)
+
+#. `@bjlittle`_ added :ref:`lenient cube maths <lenient maths>` support and
+   resolved several long standing major issues with cube arithmetic regarding
+   a more robust treatment of cube broadcasting, cube dimension auto-transposition,
+   and preservation of common metadata and coordinates during cube math operations.
+   Resolves :issue:`1887`, :issue:`2765`, and :issue:`3478`. (:pull:`3785`)
+
+#. `@pp-mo`_ and `@TomekTrzeciak`_ enhanced :meth:`~iris.cube.Cube.collapse` to allow a 1-D weights array when
+   collapsing over a single dimension.
+   Previously, the weights had to be the same shape as the whole cube, which could cost a lot of memory in some cases.
+   The 1-D form is supported by most weighted array statistics (such as :meth:`np.average`), so this now works
+   with the corresponding Iris schemes (in that case, :const:`~iris.analysis.MEAN`).  (:pull:`3943`)
 
 
 🐛 Bugs Fixed
 =============
 
-* `@stephenworsley`_ fixed :meth:`~iris.cube.Cube.remove_coord` to now also
-  remove derived coordinates by removing aux_factories. (:pull:`3641`)
-
-* `@jonseddon`_ fixed ``isinstance(cube, collections.Iterable)`` to now behave
-  as expected if a :class:`~iris.cube.Cube` is iterated over, while also
-  ensuring that ``TypeError`` is still raised. (Fixed by setting the
-  ``__iter__()`` method in :class:`~iris.cube.Cube` to ``None``).
-  (:pull:`3656`)
-
-* `@stephenworsley`_ enabled cube concatenation along an axis shared by cell
-  measures; these cell measures are now concatenated together in the resulting
-  cube. Such a scenario would previously cause concatenation to inappropriately
-  fail. (:pull:`3566`)
-
-* `@stephenworsley`_ newly included :class:`~iris.coords.CellMeasure`\ s in
-  :class:`~iris.cube.Cube` copy operations. Previously copying a
-  :class:`~iris.cube.Cube` would ignore any attached
-  :class:`~iris.coords.CellMeasure`. (:pull:`3546`)
-
-* `@bjlittle`_ set a :class:`~iris.coords.CellMeasure`'s
-  ``measure`` attribute to have a default value of ``area``.
-  Previously, the ``measure`` was provided as a keyword argument to
-  :class:`~iris.coords.CellMeasure` with a default value of ``None``, which
-  caused a ``TypeError`` when no ``measure`` was provided, since ``area`` or
-  ``volume`` are the only accepted values. (:pull:`3533`)
-
-* `@trexfeathers`_ set **all** plot types in :mod:`iris.plot` to now use
-  `matplotlib.dates.date2num`_ to format date/time coordinates for use on a plot
-  axis (previously :meth:`~iris.plot.pcolor` and :meth:`~iris.plot.pcolormesh`
-  did not include this behaviour). (:pull:`3762`)
-
-* `@trexfeathers`_ changed date/time axis labels in :mod:`iris.quickplot` to
-  now **always** be based on the ``epoch`` used in `matplotlib.dates.date2num`_
-  (previously would take the unit from a time coordinate, if present, even
-  though the coordinate's value had been changed via ``date2num``).
-  (:pull:`3762`)
-
-* `@pp-mo`_ newly included attributes of cell measures in NETCDF-CF
-  file loading; they were previously being discarded. They are now available on
-  the :class:`~iris.coords.CellMeasure` in the loaded :class:`~iris.cube.Cube`.
-  (:pull:`3800`)
-
-* `@pp-mo`_ fixed the netcdf loader to now handle any grid-mapping
-  variables with missing ``false_easting`` and ``false_northing`` properties,
-  which was previously failing for some coordinate systems. See :issue:`3629`.
-  (:pull:`3804`)
-
-* `@stephenworsley`_ changed the way tick labels are assigned from string coords.
-  Previously, the first tick label would occasionally be duplicated. This also
-  removes the use of Matplotlib's deprecated ``IndexFormatter``. (:pull:`3857`)
-
-* `@znicholls`_ fixed :meth:`~iris.quickplot._title` to only check 
-  ``units.is_time_reference`` if the ``units`` symbol is not used. (:pull:`3902`)
-
-* `@rcomer`_ fixed a bug whereby numpy array type attributes on a cube's 
-  coordinates could prevent printing it.  See :issue:`3921`.  (:pull:`3922`)
+#. `@stephenworsley`_ fixed :meth:`~iris.cube.Cube.remove_coord` to now also
+   remove derived coordinates by removing aux_factories. (:pull:`3641`)
+
+#. `@jonseddon`_ fixed ``isinstance(cube, collections.Iterable)`` to now behave
+   as expected if a :class:`~iris.cube.Cube` is iterated over, while also
+   ensuring that ``TypeError`` is still raised. (Fixed by setting the
+   ``__iter__()`` method in :class:`~iris.cube.Cube` to ``None``).
+   (:pull:`3656`)
+
+#. `@stephenworsley`_ enabled cube concatenation along an axis shared by cell
+   measures; these cell measures are now concatenated together in the resulting
+   cube. Such a scenario would previously cause concatenation to inappropriately
+   fail. (:pull:`3566`)
+
+#. `@stephenworsley`_ newly included :class:`~iris.coords.CellMeasure`\ s in
+   :class:`~iris.cube.Cube` copy operations. Previously copying a
+   :class:`~iris.cube.Cube` would ignore any attached
+   :class:`~iris.coords.CellMeasure`. (:pull:`3546`)
+
+#. `@bjlittle`_ set a :class:`~iris.coords.CellMeasure`'s
+   ``measure`` attribute to have a default value of ``area``.
+   Previously, the ``measure`` was provided as a keyword argument to
+   :class:`~iris.coords.CellMeasure` with a default value of ``None``, which
+   caused a ``TypeError`` when no ``measure`` was provided, since ``area`` or
+   ``volume`` are the only accepted values. (:pull:`3533`)
+
+#. `@trexfeathers`_ set **all** plot types in :mod:`iris.plot` to now use
+   :obj:`matplotlib.dates.date2num` to format date/time coordinates for use on a plot
+   axis (previously :meth:`~iris.plot.pcolor` and :meth:`~iris.plot.pcolormesh`
+   did not include this behaviour). (:pull:`3762`)
+
+#. `@trexfeathers`_ changed date/time axis labels in :mod:`iris.quickplot` to
+   now **always** be based on the ``epoch`` used in :obj:`matplotlib.dates.date2num`
+   (previously would take the unit from a time coordinate, if present, even
+   though the coordinate's value had been changed via ``date2num``).
+   (:pull:`3762`)
+
+#. `@pp-mo`_ newly included attributes of cell measures in NETCDF-CF
+   file loading; they were previously being discarded. They are now available on
+   the :class:`~iris.coords.CellMeasure` in the loaded :class:`~iris.cube.Cube`.
+   (:pull:`3800`)
+
+#. `@pp-mo`_ fixed the netcdf loader to now handle any grid-mapping
+   variables with missing ``false_easting`` and ``false_northing`` properties,
+   which was previously failing for some coordinate systems. See :issue:`3629`.
+   (:pull:`3804`)
+
+#. `@stephenworsley`_ changed the way tick labels are assigned from string coords.
+   Previously, the first tick label would occasionally be duplicated. This also
+   removes the use of the deprecated `matplotlib`_ ``IndexFormatter``. (:pull:`3857`)
+
+#. `@znicholls`_ fixed :meth:`~iris.quickplot._title` to only check
+   ``units.is_time_reference`` if the ``units`` symbol is not used. (:pull:`3902`)
+
+#. `@rcomer`_ fixed a bug whereby numpy array type attributes on a cube's
+   coordinates could prevent printing it.  See :issue:`3921`.  (:pull:`3922`)
 
 .. _whatsnew 3.0.1 changes:
 
 💣 Incompatible Changes
 =======================
 
-* `@pp-mo`_ rationalised :class:`~iris.cube.CubeList` extraction
-  methods:
-
-  The former method ``iris.cube.CubeList.extract_strict``, and the ``strict``
-  keyword of the :meth:`~iris.cube.CubeList.extract` method have been removed,
-  and are replaced by the new routines :meth:`~iris.cube.CubeList.extract_cube`
-  and :meth:`~iris.cube.CubeList.extract_cubes`.
-  The new routines perform the same operation, but in a style more like other
-  ``Iris`` functions such as :meth:`~iris.load_cube` and :meth:`~iris.load_cubes`.
-  Unlike ``strict`` extraction, the type of return value is now completely
-  consistent : :meth:`~iris.cube.CubeList.extract_cube` always returns a
-  :class:`~iris.cube.Cube`, and :meth:`~iris.cube.CubeList.extract_cubes`
-  always returns an :class:`iris.cube.CubeList` of a length equal to the
-  number of constraints. (:pull:`3715`)
-
-* `@pp-mo`_ removed the former function
-  ``iris.analysis.coord_comparison``. (:pull:`3562`)
-
-* `@bjlittle`_ moved the
-  :func:`iris.experimental.equalise_cubes.equalise_attributes` function from
-  the :mod:`iris.experimental` module into the :mod:`iris.util` module.  Please
-  use the :func:`iris.util.equalise_attributes` function instead.
-  (:pull:`3527`)
-
-* `@bjlittle`_ removed the module ``iris.experimental.concatenate``. In
-  ``v1.6.0`` the experimental ``concatenate`` functionality was moved to the
-  :meth:`iris.cube.CubeList.concatenate` method.  Since then, calling the
-  :func:`iris.experimental.concatenate.concatenate` function raised an
-  exception. (:pull:`3523`)
-
-* `@stephenworsley`_ changed the default units of :class:`~iris.coords.DimCoord` 
-  and :class:`~iris.coords.AuxCoord` from `"1"` to `"unknown"`.  (:pull:`3795`)
-
-* `@stephenworsley`_ changed Iris objects loaded from NetCDF-CF files to have
-  ``units='unknown'`` where the corresponding NetCDF variable has no ``units``
-  property. Previously these cases defaulted to ``units='1'``.
-  This affects loading of coordinates whose file variable has no "units"
-  attribute (not valid, under `CF units rules`_):  These will now have units
-  of `"unknown"`, rather than `"1"`, which **may prevent the creation of
-  a hybrid vertical coordinate**.  While these cases used to "work", this was
-  never really correct behaviour. (:pull:`3795`)
-
-* `@SimonPeatman`_ added attribute ``var_name`` to coordinates created by the
-  :func:`iris.analysis.trajectory.interpolate` function.  This prevents
-  duplicate coordinate errors in certain circumstances. (:pull:`3718`)
-
-* `@bjlittle`_ aligned the :func:`iris.analysis.maths.apply_ufunc` with the
-  rest of the :mod:`iris.analysis.maths` API by changing its keyword argument
-  from ``other_cube`` to ``other``. (:pull:`3785`)
-
-* `@bjlittle`_ changed the :meth:`iris.analysis.maths.IFunc.__call__` to ignore
-  any surplus ``other`` keyword argument for a ``data_func`` that requires
-  **only one** argument. This aligns the behaviour of
-  :meth:`iris.analysis.maths.IFunc.__call__` with
-  :func:`~iris.analysis.maths.apply_ufunc`. Previously a ``ValueError``
-  exception was raised. (:pull:`3785`)
+#. `@pp-mo`_ rationalised :class:`~iris.cube.CubeList` extraction
+   methods:
+
+   The former method ``iris.cube.CubeList.extract_strict``, and the ``strict``
+   keyword of the :meth:`~iris.cube.CubeList.extract` method have been removed,
+   and are replaced by the new routines :meth:`~iris.cube.CubeList.extract_cube`
+   and :meth:`~iris.cube.CubeList.extract_cubes`.
+   The new routines perform the same operation, but in a style more like other
+   ``Iris`` functions such as :meth:`~iris.load_cube` and :meth:`~iris.load_cubes`.
+   Unlike ``strict`` extraction, the type of return value is now completely
+   consistent : :meth:`~iris.cube.CubeList.extract_cube` always returns a
+   :class:`~iris.cube.Cube`, and :meth:`~iris.cube.CubeList.extract_cubes`
+   always returns an :class:`iris.cube.CubeList` of a length equal to the
+   number of constraints. (:pull:`3715`)
+
+#. `@pp-mo`_ removed the former function
+   ``iris.analysis.coord_comparison``. (:pull:`3562`)
+
+#. `@bjlittle`_ moved the
+   :func:`iris.experimental.equalise_cubes.equalise_attributes` function from
+   the :mod:`iris.experimental` module into the :mod:`iris.util` module.  Please
+   use the :func:`iris.util.equalise_attributes` function instead.
+   (:pull:`3527`)
+
+#. `@bjlittle`_ removed the module ``iris.experimental.concatenate``. In
+   ``v1.6.0`` the experimental ``concatenate`` functionality was moved to the
+   :meth:`iris.cube.CubeList.concatenate` method.  Since then, calling the
+   :func:`iris.experimental.concatenate.concatenate` function raised an
+   exception. (:pull:`3523`)
+
+#. `@stephenworsley`_ changed the default units of :class:`~iris.coords.DimCoord`
+   and :class:`~iris.coords.AuxCoord` from `"1"` to `"unknown"`.  (:pull:`3795`)
+
+#. `@stephenworsley`_ changed Iris objects loaded from NetCDF-CF files to have
+   ``units='unknown'`` where the corresponding NetCDF variable has no ``units``
+   property. Previously these cases defaulted to ``units='1'``.
+   This affects loading of coordinates whose file variable has no "units"
+   attribute (not valid, under `CF units rules`_):  These will now have units
+   of `"unknown"`, rather than `"1"`, which **may prevent the creation of
+   a hybrid vertical coordinate**.  While these cases used to "work", this was
+   never really correct behaviour. (:pull:`3795`)
+
+#. `@SimonPeatman`_ added attribute ``var_name`` to coordinates created by the
+   :func:`iris.analysis.trajectory.interpolate` function.  This prevents
+   duplicate coordinate errors in certain circumstances. (:pull:`3718`)
+
+#. `@bjlittle`_ aligned the :func:`iris.analysis.maths.apply_ufunc` with the
+   rest of the :mod:`iris.analysis.maths` API by changing its keyword argument
+   from ``other_cube`` to ``other``. (:pull:`3785`)
+
+#. `@bjlittle`_ changed the :meth:`iris.analysis.maths.IFunc.__call__` to ignore
+   any surplus ``other`` keyword argument for a ``data_func`` that requires
+   **only one** argument. This aligns the behaviour of
+   :meth:`iris.analysis.maths.IFunc.__call__` with
+   :func:`~iris.analysis.maths.apply_ufunc`. Previously a ``ValueError``
+   exception was raised. (:pull:`3785`)
 
 
 .. _whatsnew 3.0.1 deprecations:
@@ -265,48 +264,48 @@ This document explains the changes made to Iris for this release
 🔥 Deprecations
 ===============
 
-* `@stephenworsley`_ removed the deprecated :class:`iris.Future` flags
-  ``cell_date_time_objects``, ``netcdf_promote``, ``netcdf_no_unlimited`` and
-  ``clip_latitudes``. (:pull:`3459`)
+#. `@stephenworsley`_ removed the deprecated :class:`iris.Future` flags
+   ``cell_date_time_objects``, ``netcdf_promote``, ``netcdf_no_unlimited`` and
+   ``clip_latitudes``. (:pull:`3459`)
 
-* `@stephenworsley`_ changed :attr:`iris.fileformats.pp.PPField.lbproc` to be an
-  ``int``. The deprecated attributes ``flag1``, ``flag2`` etc. have been
-  removed from it. (:pull:`3461`)
+#. `@stephenworsley`_ changed :attr:`iris.fileformats.pp.PPField.lbproc` to be an
+   ``int``. The deprecated attributes ``flag1``, ``flag2`` etc. have been
+   removed from it. (:pull:`3461`)
 
-* `@bjlittle`_ deprecated :func:`~iris.util.as_compatible_shape` in preference
-  for :class:`~iris.common.resolve.Resolve` e.g., ``Resolve(src, tgt)(tgt.core_data())``.
-  The :func:`~iris.util.as_compatible_shape` function will be removed in a future
-  release of Iris. (:pull:`3892`)
+#. `@bjlittle`_ deprecated :func:`~iris.util.as_compatible_shape` in preference
+   for :class:`~iris.common.resolve.Resolve` e.g., ``Resolve(src, tgt)(tgt.core_data())``.
+   The :func:`~iris.util.as_compatible_shape` function will be removed in a future
+   release of Iris. (:pull:`3892`)
 
 
 🔗 Dependencies
 ===============
 
-* `@stephenworsley`_, `@trexfeathers`_ and `@bjlittle`_ removed ``Python2``
-  support, modernising the codebase by switching to exclusive ``Python3``
-  support. (:pull:`3513`)
+#. `@stephenworsley`_, `@trexfeathers`_ and `@bjlittle`_ removed ``Python2``
+   support, modernising the codebase by switching to exclusive ``Python3``
+   support. (:pull:`3513`)
 
-* `@bjlittle`_ improved the developer set up process. Configuring Iris and
-  :ref:`installing_from_source` as a developer with all the required package
-  dependencies is now easier with our curated conda environment YAML files.
-  (:pull:`3812`)
+#. `@bjlittle`_ improved the developer set up process. Configuring Iris and
+   :ref:`installing_from_source` as a developer with all the required package
+   dependencies is now easier with our curated conda environment YAML files.
+   (:pull:`3812`)
 
-* `@stephenworsley`_ pinned Iris to require `Dask`_ ``>=2.0``. (:pull:`3460`)
+#. `@stephenworsley`_ pinned Iris to require `Dask`_ ``>=2.0``. (:pull:`3460`)
 
-* `@stephenworsley`_ and `@trexfeathers`_ pinned Iris to require
-  `Cartopy`_ ``>=0.18``, in order to remain compatible with the latest version
-  of `Matplotlib`_. (:pull:`3762`)
+#. `@stephenworsley`_ and `@trexfeathers`_ pinned Iris to require
+   `Cartopy`_ ``>=0.18``, in order to remain compatible with the latest version
+   of `matplotlib`_. (:pull:`3762`)
 
-* `@bjlittle`_ unpinned Iris to use the latest version of `Matplotlib`_.
-  Supporting ``Iris`` for both ``Python2`` and ``Python3`` had resulted in
-  pinning our dependency on `Matplotlib`_ at ``v2.x``.  But this is no longer
-  necessary now that ``Python2`` support has been dropped. (:pull:`3468`)
+#. `@bjlittle`_ unpinned Iris to use the latest version of `matplotlib`_.
+   Supporting ``Iris`` for both ``Python2`` and ``Python3`` had resulted in
+   pinning our dependency on `matplotlib`_ at ``v2.x``.  But this is no longer
+   necessary now that ``Python2`` support has been dropped. (:pull:`3468`)
 
-* `@stephenworsley`_ and `@trexfeathers`_ unpinned Iris to use the latest version
-  of `Proj`_. (:pull:`3762`)
+#. `@stephenworsley`_ and `@trexfeathers`_ unpinned Iris to use the latest version
+   of `Proj`_. (:pull:`3762`)
 
-* `@stephenworsley`_ and `@trexfeathers`_ removed GDAL from the extensions
-  dependency group. We no longer consider it to be an extension. (:pull:`3762`)
+#. `@stephenworsley`_ and `@trexfeathers`_ removed GDAL from the extensions
+   dependency group. We no longer consider it to be an extension. (:pull:`3762`)
 
 
 .. _whatsnew 3.0.1 docs:
@@ -314,161 +313,162 @@ This document explains the changes made to Iris for this release
 📚 Documentation
 ================
 
-* `@tkknight`_ moved the
-  :ref:`sphx_glr_generated_gallery_oceanography_plot_orca_projection.py`
-  from the general part of the gallery to oceanography. (:pull:`3761`)
+#. `@tkknight`_ moved the
+   :ref:`sphx_glr_generated_gallery_oceanography_plot_orca_projection.py`
+   from the general part of the gallery to oceanography. (:pull:`3761`)
 
-* `@tkknight`_ updated documentation to use a modern sphinx theme and be
-  served from https://scitools-iris.readthedocs.io/en/latest/. (:pull:`3752`)
+#. `@tkknight`_ updated documentation to use a modern sphinx theme and be
+   served from https://scitools-iris.readthedocs.io/en/latest/. (:pull:`3752`)
 
-* `@bjlittle`_ added support for the `black`_ code formatter. This is
-  now automatically checked on GitHub PRs, replacing the older, unittest-based
-  ``iris.tests.test_coding_standards.TestCodeFormat``. Black provides automatic
-  code format correction for most IDEs.  See the new developer guide section on
-  :ref:`code_formatting`. (:pull:`3518`)
+#. `@bjlittle`_ added support for the `black`_ code formatter. This is
+   now automatically checked on GitHub PRs, replacing the older, unittest-based
+   ``iris.tests.test_coding_standards.TestCodeFormat``. Black provides automatic
+   code format correction for most IDEs.  See the new developer guide section on
+   :ref:`code_formatting`. (:pull:`3518`)
 
-* `@tkknight`_ and `@trexfeathers`_ refreshed the :ref:`whats_new_contributions`
-  for the :ref:`iris_whatsnew`. This includes always creating the ``latest``
-  what's new page so it appears on the latest documentation at
-  https://scitools-iris.readthedocs.io/en/latest/whatsnew. This resolves
-  :issue:`2104`, :issue:`3451`, :issue:`3818`, :issue:`3837`.  Also updated the
-  :ref:`iris_development_releases_steps` to follow when making a release.
-  (:pull:`3769`, :pull:`3838`, :pull:`3843`)
+#. `@tkknight`_ and `@trexfeathers`_ refreshed the :ref:`whats_new_contributions`
+   for the :ref:`iris_whatsnew`. This includes always creating the ``latest``
+   what's new page so it appears on the latest documentation at
+   https://scitools-iris.readthedocs.io/en/latest/whatsnew. This resolves
+   :issue:`2104`, :issue:`3451`, :issue:`3818`, :issue:`3837`.  Also updated the
+   :ref:`iris_development_releases_steps` to follow when making a release.
+   (:pull:`3769`, :pull:`3838`, :pull:`3843`)
 
-* `@tkknight`_ enabled the PDF creation of the documentation on the
-  `Read the Docs`_ service. The PDF may be accessed by clicking on the version
-  at the bottom of the side bar, then selecting ``PDF`` from the ``Downloads``
-  section. (:pull:`3765`)
+#. `@tkknight`_ enabled the PDF creation of the documentation on the
+   `Read the Docs`_ service. The PDF may be accessed by clicking on the version
+   at the bottom of the side bar, then selecting ``PDF`` from the ``Downloads``
+   section. (:pull:`3765`)
 
-* `@stephenworsley`_ added a warning to the
-  :func:`iris.analysis.cartography.project` function regarding its behaviour on
-  projections with non-rectangular boundaries. (:pull:`3762`)
+#. `@stephenworsley`_ added a warning to the
+   :func:`iris.analysis.cartography.project` function regarding its behaviour on
+   projections with non-rectangular boundaries. (:pull:`3762`)
 
-* `@stephenworsley`_ added the :ref:`cube_maths_combining_units` section to the
-  user guide to clarify how ``Units`` are handled during cube arithmetic.
-  (:pull:`3803`)
+#. `@stephenworsley`_ added the :ref:`cube_maths_combining_units` section to the
+   user guide to clarify how ``Units`` are handled during cube arithmetic.
+   (:pull:`3803`)
 
-* `@tkknight`_ overhauled the :ref:`developers_guide` including information on
-  getting involved in becoming a contributor and general structure of the
-  guide.  This resolves :issue:`2170`, :issue:`2331`, :issue:`3453`,
-  :issue:`314`, :issue:`2902`. (:pull:`3852`)
+#. `@tkknight`_ overhauled the :ref:`developers_guide` including information on
+   getting involved in becoming a contributor and general structure of the
+   guide.  This resolves :issue:`2170`, :issue:`2331`, :issue:`3453`,
+   :issue:`314`, :issue:`2902`. (:pull:`3852`)
 
-* `@rcomer`_ added argument descriptions to the :class:`~iris.coords.DimCoord`
-  docstring. (:pull:`3681`)
+#. `@rcomer`_ added argument descriptions to the :class:`~iris.coords.DimCoord`
+   docstring. (:pull:`3681`)
 
-* `@tkknight`_ added two url's to be ignored for the ``make linkcheck``.  This
-  will ensure the Iris github project is not repeatedly hit during the
-  linkcheck for issues and pull requests as it can result in connection
-  refused and thus travis-ci_ job failures.  For more information on linkcheck,
-  see :ref:`contributing.documentation.testing`.  (:pull:`3873`)
+#. `@tkknight`_ added two url's to be ignored for the ``make linkcheck``.  This
+   will ensure the Iris github project is not repeatedly hit during the
+   linkcheck for issues and pull requests as it can result in connection
+   refused and thus travis-ci_ job failures.  For more information on linkcheck,
+   see :ref:`contributing.documentation.testing`.  (:pull:`3873`)
 
-* `@tkknight`_ enabled the napolean_ package that is used by sphinx_ to cater
-  for the existing google style docstrings and to also allow for `numpy`_
-  docstrings.  This resolves :issue:`3841`. (:pull:`3871`)
+#. `@tkknight`_ enabled the napolean_ package that is used by sphinx_ to cater
+   for the existing google style docstrings and to also allow for `numpy`_
+   docstrings.  This resolves :issue:`3841`. (:pull:`3871`)
 
-* `@tkknight`_ configured ``sphinx-build`` to promote warnings to errors when
-  building the documentation via ``make html``.  This will minimise technical
-  debt accruing for the documentation.  (:pull:`3877`)
+#. `@tkknight`_ configured ``sphinx-build`` to promote warnings to errors when
+   building the documentation via ``make html``.  This will minimise technical
+   debt accruing for the documentation.  (:pull:`3877`)
 
-* `@tkknight`_ updated :ref:`installing_iris` to include a reference to
-  Windows Subsystem for Linux. (:pull:`3885`)
+#. `@tkknight`_ updated :ref:`installing_iris` to include a reference to
+   Windows Subsystem for Linux. (:pull:`3885`)
 
-* `@tkknight`_ updated the :ref:`iris_docs` homepage to include panels so the
-  links are more visible to users.  This uses the sphinx-panels_ extension.
-  (:pull:`3884`)
+#. `@tkknight`_ updated the :ref:`iris_docs` homepage to include panels so the
+   links are more visible to users.  This uses the sphinx-panels_ extension.
+   (:pull:`3884`)
 
-* `@bjlittle`_ created the :ref:`Further topics <further topics>` section and
-  included documentation for :ref:`metadata`, :ref:`lenient metadata`, and
-  :ref:`lenient maths`. (:pull:`3890`)
+#. `@bjlittle`_ created the :ref:`Further topics <further topics>` section and
+   included documentation for :ref:`metadata`, :ref:`lenient metadata`, and
+   :ref:`lenient maths`. (:pull:`3890`)
 
-* `@jonseddon`_ updated the CF version of the netCDF saver in the 
-  :ref:`saving_iris_cubes` section and in the equivalent function docstring.
-  (:pull:`3925`)
+#. `@jonseddon`_ updated the CF version of the netCDF saver in the
+   :ref:`saving_iris_cubes` section and in the equivalent function docstring.
+   (:pull:`3925`)
 
-* `@bjlittle`_ applied `Title Case Capitalization`_ to the documentation.
-  (:pull:`3940`)
+#. `@bjlittle`_ applied `Title Case Capitalization`_ to the documentation.
+   (:pull:`3940`)
 
 
 💼 Internal
 ===========
 
-* `@pp-mo`_ and `@lbdreyer`_ removed all Iris test dependencies on `iris-grib`_
-  by transferring all relevant content to the `iris-grib`_ repository. (:pull:`3662`,
-  :pull:`3663`, :pull:`3664`, :pull:`3665`, :pull:`3666`, :pull:`3669`,
-  :pull:`3670`, :pull:`3671`, :pull:`3672`, :pull:`3742`, :pull:`3746`)
-
-* `@lbdreyer`_ and `@pp-mo`_ overhauled the handling of dimensional
-  metadata to remove duplication. (:pull:`3422`, :pull:`3551`)
+#. `@pp-mo`_ and `@lbdreyer`_ removed all Iris test dependencies on `iris-grib`_
+   by transferring all relevant content to the `iris-grib`_ repository. (:pull:`3662`,
+   :pull:`3663`, :pull:`3664`, :pull:`3665`, :pull:`3666`, :pull:`3669`,
+   :pull:`3670`, :pull:`3671`, :pull:`3672`, :pull:`3742`, :pull:`3746`)
 
-* `@trexfeathers`_ simplified the standard license header for all files, which
-  removes the need to repeatedly update year numbers in the header.
-  (:pull:`3489`)
+#. `@lbdreyer`_ and `@pp-mo`_ overhauled the handling of dimensional
+   metadata to remove duplication. (:pull:`3422`, :pull:`3551`)
 
-* `@stephenworsley`_ changed the numerical values in tests involving the
-  Robinson projection due to improvements made in
-  `Proj`_. (:pull:`3762`) (see also `Proj#1292`_ and `Proj#2151`_)
+#. `@trexfeathers`_ simplified the standard license header for all files, which
+   removes the need to repeatedly update year numbers in the header.
+   (:pull:`3489`)
 
-* `@stephenworsley`_ changed tests to account for more detailed descriptions of
-  projections in `GDAL`_. (:pull:`3762`) (see also `GDAL#1185`_)
+#. `@stephenworsley`_ changed the numerical values in tests involving the
+   Robinson projection due to improvements made in
+   `Proj`_. (:pull:`3762`) (see also `Proj#1292`_ and `Proj#2151`_)
 
-* `@stephenworsley`_ changed tests to account for `GDAL`_ now saving fill values
-  for data without masked points. (:pull:`3762`)
+#. `@stephenworsley`_ changed tests to account for more detailed descriptions of
+   projections in `GDAL`_. (:pull:`3762`) (see also `GDAL#1185`_)
 
-* `@trexfeathers`_ changed every graphics test that includes `Cartopy's coastlines`_
-  to account for new adaptive coastline scaling. (:pull:`3762`)
-  (see also `Cartopy#1105`_)
+#. `@stephenworsley`_ changed tests to account for `GDAL`_ now saving fill values
+   for data without masked points. (:pull:`3762`)
 
-* `@trexfeathers`_ changed graphics tests to account for some new default
-  grid-line spacing in `Cartopy`_. (:pull:`3762`) (see also `Cartopy#1117`_)
+#. `@trexfeathers`_ changed every graphics test that includes `Cartopy's coastlines`_
+   to account for new adaptive coastline scaling. (:pull:`3762`)
+   (see also `Cartopy#1105`_)
 
-* `@trexfeathers`_ added additional acceptable graphics test targets to account
-  for very minor changes in `Matplotlib`_ version ``3.3`` (colormaps, fonts and
-  axes borders). (:pull:`3762`)
+#. `@trexfeathers`_ changed graphics tests to account for some new default
+   grid-line spacing in `Cartopy`_. (:pull:`3762`) (see also `Cartopy#1117`_)
 
-* `@rcomer`_ corrected the Matplotlib backend in Iris tests to ignore
-  `matplotlib.rcdefaults`_, instead the tests will **always** use ``agg``.
-  (:pull:`3846`)
+#. `@trexfeathers`_ added additional acceptable graphics test targets to account
+   for very minor changes in `matplotlib`_ version ``3.3`` (colormaps, fonts and
+   axes borders). (:pull:`3762`)
 
-* `@bjlittle`_ migrated the `black`_ support from ``19.10b0`` to ``20.8b1``.
-  (:pull:`3866`)
+#. `@rcomer`_ corrected the `matplotlib`_ backend in Iris tests to ignore
+   :obj:`matplotlib.rcdefaults`, instead the tests will **always** use ``agg``.
+   (:pull:`3846`)
 
-* `@lbdreyer`_ updated the CF standard name table to the latest version: `v75`_.
-  (:pull:`3867`)
+#. `@bjlittle`_ migrated the `black`_ support from ``19.10b0`` to ``20.8b1``.
+   (:pull:`3866`)
 
-* `@bjlittle`_ added :pep:`517` and :pep:`518` support for building and
-  installing Iris, in particular to handle the `PyKE`_ package dependency.
-  (:pull:`3812`)
+#. `@lbdreyer`_ updated the CF standard name table to the latest version: `v75`_.
+   (:pull:`3867`)
 
-* `@bjlittle`_ added metadata support for comparing :attr:`~iris.cube.Cube.attributes`
-  dictionaries that contain `numpy`_ arrays using `xxHash`_, an extremely fast
-  non-cryptographic hash algorithm, running at RAM speed limits.
+#. `@bjlittle`_ added :pep:`517` and :pep:`518` support for building and
+   installing Iris, in particular to handle the `PyKE`_ package dependency.
+   (:pull:`3812`)
 
-* `@bjlittle`_ added the ``iris.tests.assertDictEqual`` method to override
-  :meth:`unittest.TestCase.assertDictEqual` in order to cope with testing
-  metadata :attr:`~iris.cube.Cube.attributes` dictionary comparison where
-  the value of a key may be a `numpy`_ array. (:pull:`3785`)
+#. `@bjlittle`_ added metadata support for comparing :attr:`~iris.cube.Cube.attributes`
+   dictionaries that contain `numpy`_ arrays using `xxHash`_, an extremely fast
+   non-cryptographic hash algorithm, running at RAM speed limits.
 
-* `@bjlittle`_ added the :func:`~iris.config.get_logger` function for creating
-  a generic :class:`logging.Logger` with a :class:`logging.StreamHandler` and
-  custom :class:`logging.Formatter`. (:pull:`3785`)
+#. `@bjlittle`_ added the ``iris.tests.assertDictEqual`` method to override
+   :meth:`unittest.TestCase.assertDictEqual` in order to cope with testing
+   metadata :attr:`~iris.cube.Cube.attributes` dictionary comparison where
+   the value of a key may be a `numpy`_ array. (:pull:`3785`)
 
-* `@owena11`_ identified and optimised a bottleneck in ``FieldsFile`` header
-  loading due to the use of :func:`numpy.fromfile`. (:pull:`3791`)
+#. `@bjlittle`_ added the :func:`~iris.config.get_logger` function for creating
+   a generic :class:`logging.Logger` with a :class:`logging.StreamHandler` and
+   custom :class:`logging.Formatter`. (:pull:`3785`)
 
-* `@znicholls`_ added a test for plotting with the label being taken from the unit's symbol, see :meth:`~iris.tests.test_quickplot.TestLabels.test_pcolormesh_str_symbol` (:pull:`3902`).
+#. `@owena11`_ identified and optimised a bottleneck in ``FieldsFile`` header
+   loading due to the use of :func:`numpy.fromfile`. (:pull:`3791`)
 
-* `@znicholls`_ made :func:`~iris.tests.idiff.step_over_diffs` robust to hyphens (``-``) in the input path (i.e. the ``result_dir`` argument) (:pull:`3902`).
+#. `@znicholls`_ added a test for plotting with the label being taken from the unit's symbol,
+   see :meth:`~iris.tests.test_quickplot.TestLabels.test_pcolormesh_str_symbol` (:pull:`3902`).
 
-* `@bjlittle`_ migrated the CIaaS from `travis-ci`_ to `cirrus-ci`_, and removed `stickler-ci`_ support. (:pull:`3928`)
+#. `@znicholls`_ made :func:`~iris.tests.idiff.step_over_diffs` robust to hyphens (``-``) in
+   the input path (i.e. the ``result_dir`` argument) (:pull:`3902`).
 
-* `@bjlittle`_ introduced `nox`_ as a common and easy entry-point for test automation.
-  It can be used both from `cirrus-ci`_ in the cloud, and locally by the developer to
-  run the Iris tests, the doc-tests, the gallery doc-tests, and lint Iris
-  with `flake8`_ and `black`_. (:pull:`3928`)
+#. `@bjlittle`_ migrated the CIaaS from `travis-ci`_ to `cirrus-ci`_, and removed `stickler-ci`_
+   support. (:pull:`3928`)
 
+#. `@bjlittle`_ introduced `nox`_ as a common and easy entry-point for test automation.
+   It can be used both from `cirrus-ci`_ in the cloud, and locally by the developer to
+   run the Iris tests, the doc-tests, the gallery doc-tests, and lint Iris
+   with `flake8`_ and `black`_. (:pull:`3928`)
 
 .. _Read the Docs: https://scitools-iris.readthedocs.io/en/latest/
-.. _Matplotlib: https://matplotlib.org/
 .. _CF units rules: https://cfconventions.org/Data/cf-conventions/cf-conventions-1.8/cf-conventions.html#units
 .. _CF Ancillary Data: https://cfconventions.org/Data/cf-conventions/cf-conventions-1.8/cf-conventions.html#ancillary-data
 .. _Quality Flags: https://cfconventions.org/Data/cf-conventions/cf-conventions-1.8/cf-conventions.html#flags
@@ -478,7 +478,6 @@ This document explains the changes made to Iris for this release
 .. _Cartopy#1105: https://github.com/SciTools/cartopy/pull/1105
 .. _Cartopy#1117: https://github.com/SciTools/cartopy/pull/1117
 .. _Dask: https://github.com/dask/dask
-.. _matplotlib.dates.date2num: https://matplotlib.org/api/dates_api.html#matplotlib.dates.date2num
 .. _Proj: https://github.com/OSGeo/PROJ
 .. _black: https://black.readthedocs.io/en/stable/
 .. _Proj#1292: https://github.com/OSGeo/PROJ/pull/1292
@@ -508,7 +507,6 @@ This document explains the changes made to Iris for this release
 .. _numpy: https://github.com/numpy/numpy
 .. _xxHash: https://github.com/Cyan4973/xxHash
 .. _PyKE: https://pypi.org/project/scitools-pyke/
-.. _matplotlib.rcdefaults: https://matplotlib.org/3.1.1/api/matplotlib_configuration_api.html?highlight=rcdefaults#matplotlib.rcdefaults
 .. _@owena11: https://github.com/owena11
 .. _GitHub: https://github.com/SciTools/iris/issues/new/choose
 .. _readthedocs: https://readthedocs.org/
diff --git a/docs/iris/src/whatsnew/3.0.2.rst b/docs/iris/src/whatsnew/3.0.2.rst
new file mode 100644
index 0000000000..1ba6271d47
--- /dev/null
+++ b/docs/iris/src/whatsnew/3.0.2.rst
@@ -0,0 +1,552 @@
+.. include:: ../common_links.inc
+
+v3.0.2 (unreleased)
+*******************
+
+This document explains the changes made to Iris for this release
+(:doc:`View all changes <index>`.)
+
+
+.. dropdown:: :opticon:`alert` v3.0.2 Patches
+   :container: + shadow
+   :title: text-primary text-center font-weight-bold
+   :body: bg-light
+   :animate: fade-in
+   :open:
+
+   The patches included in this release include:
+
+   🐛 **Bugs Fixed**
+
+   #.
+
+   📚 **Documentation**
+
+   #. `@bjlittle`_ updated the ``intersphinx_mapping`` and fixed documentation
+      to use ``stable`` URLs for `matplotlib`_. (:pull:`4003`) [``pre-v3.1.0``]
+
+   💼 **Internal**
+
+   #. `@jamesp`_ updated a test to the latest numpy version (:pull:`3977`) [``pre-v3.1.0``]
+
+   #. `@bjlittle`_ enabled `cirrus-ci`_ compute credits for non-draft pull-requests
+      from collaborators targeting the Iris ``master`` branch. (:pull:`4007`)
+      [``pre-v3.1.0``]
+
+   #. `@bjlittle`_ added conditional task execution to `.cirrus.yml`_ to allow
+      developers to easily disable `cirrus-ci`_ tasks. See
+      :ref:`skipping Cirrus-CI tasks`. (:pull:`4019`) [``pre-v3.1.0``]
+
+   Note that, the contributions labelled ``pre-v3.1.0`` are part of the forthcoming
+   Iris v3.1.0 release, but require to be included in this patch release.
+
+
+.. dropdown:: :opticon:`alert` v3.0.1 Patches
+   :container: + shadow
+   :title: text-primary text-center font-weight-bold
+   :body: bg-light
+   :animate: fade-in
+
+   The patches included in this release include:
+
+   💼 **Internal**
+
+   #. `@bjlittle`_ gracefully promote formula terms within :mod:`~iris.aux_factory` that have ``units`` of ``unknown``
+      to ``units`` of ``1`` (dimensionless), where the formula term **must** have dimensionless ``units``. Without this
+      graceful treatment of ``units`` the resulting :class:`~iris.cube.Cube` will **not** contain the expected auxiliary
+      factory, and the associated derived coordinate will be missing. (:pull:`3965`)
+
+
+.. dropdown:: :opticon:`report` v3.0.0 Release Highlights
+   :container: + shadow
+   :title: text-primary text-center font-weight-bold
+   :body: bg-light
+   :animate: fade-in
+
+   The highlights for this major release of Iris include:
+
+   * We've finally dropped support for ``Python 2``, so welcome to ``Iris 3``
+     and ``Python 3``!
+   * We've extended our coverage of the `CF Conventions and Metadata`_ by
+     introducing support for `CF Ancillary Data`_ and `Quality Flags`_,
+   * Lazy regridding is now available for several regridding schemes,
+   * Managing and manipulating metadata within Iris is now easier and more
+     consistent thanks to the introduction of a new common metadata API,
+   * :ref:`Cube arithmetic <cube maths>` has been significantly improved with
+     regards to extended broadcasting, auto-transposition and a more lenient
+     behaviour towards handling metadata and coordinates,
+   * Our :ref:`documentation <whatsnew 3.0.2 docs>` has been refreshed,
+     restructured, revitalised and rehosted on `readthedocs`_,
+   * It's now easier than ever to :ref:`install Iris <installing_iris>`
+     as a user or a developer, and the newly revamped developers guide walks
+     you though how you can :ref:`get involved <development_where_to_start>`
+     and contribute to Iris,
+   * Also, this is a major release of Iris, so please be aware of the
+     :ref:`incompatible changes <whatsnew 3.0.2 changes>` and
+     :ref:`deprecations <whatsnew 3.0.2 deprecations>`.
+
+   And finally, get in touch with us on `GitHub`_ if you have any issues or
+   feature requests for improving Iris. Enjoy!
+
+
+📢 Announcements
+================
+
+#. Congratulations to `@bouweandela`_, `@jvegasbsc`_, and `@zklaus`_ who
+   recently became Iris core developers. They bring a wealth of expertise to the
+   team, and are using Iris to underpin `ESMValTool`_ - "*A community diagnostic
+   and performance metrics tool for routine evaluation of Earth system models
+   in CMIP*". Welcome aboard! 🎉
+
+#. Congratulations also goes to `@jonseddon`_ who recently became an Iris core
+   developer. We look forward to seeing more of your awesome contributions! 🎉
+
+
+✨ Features
+===========
+
+#. `@MoseleyS`_ greatly enhanced  the :mod:`~iris.fileformats.nimrod`
+   module to provide richer meta-data translation when loading ``Nimrod`` data
+   into cubes. This covers most known operational use-cases. (:pull:`3647`)
+
+#. `@stephenworsley`_ improved the handling of
+   :class:`iris.coords.CellMeasure`\ s in the :class:`~iris.cube.Cube`
+   statistical operations :meth:`~iris.cube.Cube.collapsed`,
+   :meth:`~iris.cube.Cube.aggregated_by` and
+   :meth:`~iris.cube.Cube.rolling_window`. These previously removed every
+   :class:`~iris.coords.CellMeasure` attached to the cube.  Now, a
+   :class:`~iris.coords.CellMeasure` will only be removed if it is associated
+   with an axis over which the statistic is being run. (:pull:`3549`)
+
+#. `@stephenworsley`_, `@pp-mo`_ and `@abooton`_ added support for
+   `CF Ancillary Data`_ variables.  These are created as
+   :class:`iris.coords.AncillaryVariable`, and appear as components of cubes
+   much like :class:`~iris.coords.AuxCoord`\ s, with the new
+   :class:`~iris.cube.Cube` methods
+   :meth:`~iris.cube.Cube.add_ancillary_variable`,
+   :meth:`~iris.cube.Cube.remove_ancillary_variable`,
+   :meth:`~iris.cube.Cube.ancillary_variable`,
+   :meth:`~iris.cube.Cube.ancillary_variables` and
+   :meth:`~iris.cube.Cube.ancillary_variable_dims`.
+   They are loaded from and saved to NetCDF-CF files.  Special support for
+   `Quality Flags`_ is also provided, to ensure they load and save with
+   appropriate units. (:pull:`3800`)
+
+#. `@bouweandela`_ implemented lazy regridding for the
+   :class:`~iris.analysis.Linear`, :class:`~iris.analysis.Nearest`, and
+   :class:`~iris.analysis.AreaWeighted` regridding schemes. (:pull:`3701`)
+
+#. `@bjlittle`_ added `logging`_ support within :mod:`iris.analysis.maths`,
+   :mod:`iris.common.metadata`, and :mod:`iris.common.resolve`. Each module
+   defines a :class:`logging.Logger` instance called ``logger`` with a default
+   ``level`` of ``INFO``. To enable ``DEBUG`` logging use
+   ``logger.setLevel("DEBUG")``. (:pull:`3785`)
+
+#. `@bjlittle`_ added the :mod:`iris.common.resolve` module, which provides
+   infrastructure to support the analysis, identification and combination
+   of metadata common between two :class:`~iris.cube.Cube` operands into a
+   single resultant :class:`~iris.cube.Cube` that will be auto-transposed,
+   and with the appropriate broadcast shape. (:pull:`3785`)
+
+#. `@bjlittle`_ added the :ref:`common metadata API <metadata>`, which provides
+   a unified treatment of metadata across Iris, and allows users to easily
+   manage and manipulate their metadata in a consistent way. (:pull:`3785`)
+
+#. `@bjlittle`_ added :ref:`lenient metadata <lenient metadata>` support, to
+   allow users to control **strict** or **lenient** metadata equivalence,
+   difference and combination. (:pull:`3785`)
+
+#. `@bjlittle`_ added :ref:`lenient cube maths <lenient maths>` support and
+   resolved several long standing major issues with cube arithmetic regarding
+   a more robust treatment of cube broadcasting, cube dimension auto-transposition,
+   and preservation of common metadata and coordinates during cube math operations.
+   Resolves :issue:`1887`, :issue:`2765`, and :issue:`3478`. (:pull:`3785`)
+
+#. `@pp-mo`_ and `@TomekTrzeciak`_ enhanced :meth:`~iris.cube.Cube.collapse` to allow a 1-D weights array when
+   collapsing over a single dimension.
+   Previously, the weights had to be the same shape as the whole cube, which could cost a lot of memory in some cases.
+   The 1-D form is supported by most weighted array statistics (such as :meth:`np.average`), so this now works
+   with the corresponding Iris schemes (in that case, :const:`~iris.analysis.MEAN`).  (:pull:`3943`)
+
+
+🐛 Bugs Fixed
+=============
+
+#. `@stephenworsley`_ fixed :meth:`~iris.cube.Cube.remove_coord` to now also
+   remove derived coordinates by removing aux_factories. (:pull:`3641`)
+
+#. `@jonseddon`_ fixed ``isinstance(cube, collections.Iterable)`` to now behave
+   as expected if a :class:`~iris.cube.Cube` is iterated over, while also
+   ensuring that ``TypeError`` is still raised. (Fixed by setting the
+   ``__iter__()`` method in :class:`~iris.cube.Cube` to ``None``).
+   (:pull:`3656`)
+
+#. `@stephenworsley`_ enabled cube concatenation along an axis shared by cell
+   measures; these cell measures are now concatenated together in the resulting
+   cube. Such a scenario would previously cause concatenation to inappropriately
+   fail. (:pull:`3566`)
+
+#. `@stephenworsley`_ newly included :class:`~iris.coords.CellMeasure`\ s in
+   :class:`~iris.cube.Cube` copy operations. Previously copying a
+   :class:`~iris.cube.Cube` would ignore any attached
+   :class:`~iris.coords.CellMeasure`. (:pull:`3546`)
+
+#. `@bjlittle`_ set a :class:`~iris.coords.CellMeasure`'s
+   ``measure`` attribute to have a default value of ``area``.
+   Previously, the ``measure`` was provided as a keyword argument to
+   :class:`~iris.coords.CellMeasure` with a default value of ``None``, which
+   caused a ``TypeError`` when no ``measure`` was provided, since ``area`` or
+   ``volume`` are the only accepted values. (:pull:`3533`)
+
+#. `@trexfeathers`_ set **all** plot types in :mod:`iris.plot` to now use
+   :obj:`matplotlib.dates.date2num` to format date/time coordinates for use on a plot
+   axis (previously :meth:`~iris.plot.pcolor` and :meth:`~iris.plot.pcolormesh`
+   did not include this behaviour). (:pull:`3762`)
+
+#. `@trexfeathers`_ changed date/time axis labels in :mod:`iris.quickplot` to
+   now **always** be based on the ``epoch`` used in :obj:`matplotlib.dates.date2num`
+   (previously would take the unit from a time coordinate, if present, even
+   though the coordinate's value had been changed via ``date2num``).
+   (:pull:`3762`)
+
+#. `@pp-mo`_ newly included attributes of cell measures in NETCDF-CF
+   file loading; they were previously being discarded. They are now available on
+   the :class:`~iris.coords.CellMeasure` in the loaded :class:`~iris.cube.Cube`.
+   (:pull:`3800`)
+
+#. `@pp-mo`_ fixed the netcdf loader to now handle any grid-mapping
+   variables with missing ``false_easting`` and ``false_northing`` properties,
+   which was previously failing for some coordinate systems. See :issue:`3629`.
+   (:pull:`3804`)
+
+#. `@stephenworsley`_ changed the way tick labels are assigned from string coords.
+   Previously, the first tick label would occasionally be duplicated. This also
+   removes the use of the deprecated `matplotlib`_ ``IndexFormatter``. (:pull:`3857`)
+
+#. `@znicholls`_ fixed :meth:`~iris.quickplot._title` to only check
+   ``units.is_time_reference`` if the ``units`` symbol is not used. (:pull:`3902`)
+
+#. `@rcomer`_ fixed a bug whereby numpy array type attributes on a cube's
+   coordinates could prevent printing it.  See :issue:`3921`.  (:pull:`3922`)
+
+.. _whatsnew 3.0.2 changes:
+
+💣 Incompatible Changes
+=======================
+
+#. `@pp-mo`_ rationalised :class:`~iris.cube.CubeList` extraction
+   methods:
+
+   The former method ``iris.cube.CubeList.extract_strict``, and the ``strict``
+   keyword of the :meth:`~iris.cube.CubeList.extract` method have been removed,
+   and are replaced by the new routines :meth:`~iris.cube.CubeList.extract_cube`
+   and :meth:`~iris.cube.CubeList.extract_cubes`.
+   The new routines perform the same operation, but in a style more like other
+   ``Iris`` functions such as :meth:`~iris.load_cube` and :meth:`~iris.load_cubes`.
+   Unlike ``strict`` extraction, the type of return value is now completely
+   consistent : :meth:`~iris.cube.CubeList.extract_cube` always returns a
+   :class:`~iris.cube.Cube`, and :meth:`~iris.cube.CubeList.extract_cubes`
+   always returns an :class:`iris.cube.CubeList` of a length equal to the
+   number of constraints. (:pull:`3715`)
+
+#. `@pp-mo`_ removed the former function
+   ``iris.analysis.coord_comparison``. (:pull:`3562`)
+
+#. `@bjlittle`_ moved the
+   :func:`iris.experimental.equalise_cubes.equalise_attributes` function from
+   the :mod:`iris.experimental` module into the :mod:`iris.util` module.  Please
+   use the :func:`iris.util.equalise_attributes` function instead.
+   (:pull:`3527`)
+
+#. `@bjlittle`_ removed the module ``iris.experimental.concatenate``. In
+   ``v1.6.0`` the experimental ``concatenate`` functionality was moved to the
+   :meth:`iris.cube.CubeList.concatenate` method.  Since then, calling the
+   :func:`iris.experimental.concatenate.concatenate` function raised an
+   exception. (:pull:`3523`)
+
+#. `@stephenworsley`_ changed the default units of :class:`~iris.coords.DimCoord`
+   and :class:`~iris.coords.AuxCoord` from `"1"` to `"unknown"`.  (:pull:`3795`)
+
+#. `@stephenworsley`_ changed Iris objects loaded from NetCDF-CF files to have
+   ``units='unknown'`` where the corresponding NetCDF variable has no ``units``
+   property. Previously these cases defaulted to ``units='1'``.
+   This affects loading of coordinates whose file variable has no "units"
+   attribute (not valid, under `CF units rules`_):  These will now have units
+   of `"unknown"`, rather than `"1"`, which **may prevent the creation of
+   a hybrid vertical coordinate**.  While these cases used to "work", this was
+   never really correct behaviour. (:pull:`3795`)
+
+#. `@SimonPeatman`_ added attribute ``var_name`` to coordinates created by the
+   :func:`iris.analysis.trajectory.interpolate` function.  This prevents
+   duplicate coordinate errors in certain circumstances. (:pull:`3718`)
+
+#. `@bjlittle`_ aligned the :func:`iris.analysis.maths.apply_ufunc` with the
+   rest of the :mod:`iris.analysis.maths` API by changing its keyword argument
+   from ``other_cube`` to ``other``. (:pull:`3785`)
+
+#. `@bjlittle`_ changed the :meth:`iris.analysis.maths.IFunc.__call__` to ignore
+   any surplus ``other`` keyword argument for a ``data_func`` that requires
+   **only one** argument. This aligns the behaviour of
+   :meth:`iris.analysis.maths.IFunc.__call__` with
+   :func:`~iris.analysis.maths.apply_ufunc`. Previously a ``ValueError``
+   exception was raised. (:pull:`3785`)
+
+
+.. _whatsnew 3.0.2 deprecations:
+
+🔥 Deprecations
+===============
+
+#. `@stephenworsley`_ removed the deprecated :class:`iris.Future` flags
+   ``cell_date_time_objects``, ``netcdf_promote``, ``netcdf_no_unlimited`` and
+   ``clip_latitudes``. (:pull:`3459`)
+
+#. `@stephenworsley`_ changed :attr:`iris.fileformats.pp.PPField.lbproc` to be an
+   ``int``. The deprecated attributes ``flag1``, ``flag2`` etc. have been
+   removed from it. (:pull:`3461`)
+
+#. `@bjlittle`_ deprecated :func:`~iris.util.as_compatible_shape` in preference
+   for :class:`~iris.common.resolve.Resolve` e.g., ``Resolve(src, tgt)(tgt.core_data())``.
+   The :func:`~iris.util.as_compatible_shape` function will be removed in a future
+   release of Iris. (:pull:`3892`)
+
+
+🔗 Dependencies
+===============
+
+#. `@stephenworsley`_, `@trexfeathers`_ and `@bjlittle`_ removed ``Python2``
+   support, modernising the codebase by switching to exclusive ``Python3``
+   support. (:pull:`3513`)
+
+#. `@bjlittle`_ improved the developer set up process. Configuring Iris and
+   :ref:`installing_from_source` as a developer with all the required package
+   dependencies is now easier with our curated conda environment YAML files.
+   (:pull:`3812`)
+
+#. `@stephenworsley`_ pinned Iris to require `Dask`_ ``>=2.0``. (:pull:`3460`)
+
+#. `@stephenworsley`_ and `@trexfeathers`_ pinned Iris to require
+   `Cartopy`_ ``>=0.18``, in order to remain compatible with the latest version
+   of `matplotlib`_. (:pull:`3762`)
+
+#. `@bjlittle`_ unpinned Iris to use the latest version of `matplotlib`_.
+   Supporting ``Iris`` for both ``Python2`` and ``Python3`` had resulted in
+   pinning our dependency on `matplotlib`_ at ``v2.x``.  But this is no longer
+   necessary now that ``Python2`` support has been dropped. (:pull:`3468`)
+
+#. `@stephenworsley`_ and `@trexfeathers`_ unpinned Iris to use the latest version
+   of `Proj`_. (:pull:`3762`)
+
+#. `@stephenworsley`_ and `@trexfeathers`_ removed GDAL from the extensions
+   dependency group. We no longer consider it to be an extension. (:pull:`3762`)
+
+
+.. _whatsnew 3.0.2 docs:
+
+📚 Documentation
+================
+
+#. `@tkknight`_ moved the
+   :ref:`sphx_glr_generated_gallery_oceanography_plot_orca_projection.py`
+   from the general part of the gallery to oceanography. (:pull:`3761`)
+
+#. `@tkknight`_ updated documentation to use a modern sphinx theme and be
+   served from https://scitools-iris.readthedocs.io/en/latest/. (:pull:`3752`)
+
+#. `@bjlittle`_ added support for the `black`_ code formatter. This is
+   now automatically checked on GitHub PRs, replacing the older, unittest-based
+   ``iris.tests.test_coding_standards.TestCodeFormat``. Black provides automatic
+   code format correction for most IDEs.  See the new developer guide section on
+   :ref:`code_formatting`. (:pull:`3518`)
+
+#. `@tkknight`_ and `@trexfeathers`_ refreshed the :ref:`whats_new_contributions`
+   for the :ref:`iris_whatsnew`. This includes always creating the ``latest``
+   what's new page so it appears on the latest documentation at
+   https://scitools-iris.readthedocs.io/en/latest/whatsnew. This resolves
+   :issue:`2104`, :issue:`3451`, :issue:`3818`, :issue:`3837`.  Also updated the
+   :ref:`iris_development_releases_steps` to follow when making a release.
+   (:pull:`3769`, :pull:`3838`, :pull:`3843`)
+
+#. `@tkknight`_ enabled the PDF creation of the documentation on the
+   `Read the Docs`_ service. The PDF may be accessed by clicking on the version
+   at the bottom of the side bar, then selecting ``PDF`` from the ``Downloads``
+   section. (:pull:`3765`)
+
+#. `@stephenworsley`_ added a warning to the
+   :func:`iris.analysis.cartography.project` function regarding its behaviour on
+   projections with non-rectangular boundaries. (:pull:`3762`)
+
+#. `@stephenworsley`_ added the :ref:`cube_maths_combining_units` section to the
+   user guide to clarify how ``Units`` are handled during cube arithmetic.
+   (:pull:`3803`)
+
+#. `@tkknight`_ overhauled the :ref:`developers_guide` including information on
+   getting involved in becoming a contributor and general structure of the
+   guide.  This resolves :issue:`2170`, :issue:`2331`, :issue:`3453`,
+   :issue:`314`, :issue:`2902`. (:pull:`3852`)
+
+#. `@rcomer`_ added argument descriptions to the :class:`~iris.coords.DimCoord`
+   docstring. (:pull:`3681`)
+
+#. `@tkknight`_ added two url's to be ignored for the ``make linkcheck``.  This
+   will ensure the Iris github project is not repeatedly hit during the
+   linkcheck for issues and pull requests as it can result in connection
+   refused and thus travis-ci_ job failures.  For more information on linkcheck,
+   see :ref:`contributing.documentation.testing`.  (:pull:`3873`)
+
+#. `@tkknight`_ enabled the napolean_ package that is used by sphinx_ to cater
+   for the existing google style docstrings and to also allow for `numpy`_
+   docstrings.  This resolves :issue:`3841`. (:pull:`3871`)
+
+#. `@tkknight`_ configured ``sphinx-build`` to promote warnings to errors when
+   building the documentation via ``make html``.  This will minimise technical
+   debt accruing for the documentation.  (:pull:`3877`)
+
+#. `@tkknight`_ updated :ref:`installing_iris` to include a reference to
+   Windows Subsystem for Linux. (:pull:`3885`)
+
+#. `@tkknight`_ updated the :ref:`iris_docs` homepage to include panels so the
+   links are more visible to users.  This uses the sphinx-panels_ extension.
+   (:pull:`3884`)
+
+#. `@bjlittle`_ created the :ref:`Further topics <further topics>` section and
+   included documentation for :ref:`metadata`, :ref:`lenient metadata`, and
+   :ref:`lenient maths`. (:pull:`3890`)
+
+#. `@jonseddon`_ updated the CF version of the netCDF saver in the
+   :ref:`saving_iris_cubes` section and in the equivalent function docstring.
+   (:pull:`3925`)
+
+#. `@bjlittle`_ applied `Title Case Capitalization`_ to the documentation.
+   (:pull:`3940`)
+
+
+💼 Internal
+===========
+
+#. `@pp-mo`_ and `@lbdreyer`_ removed all Iris test dependencies on `iris-grib`_
+   by transferring all relevant content to the `iris-grib`_ repository. (:pull:`3662`,
+   :pull:`3663`, :pull:`3664`, :pull:`3665`, :pull:`3666`, :pull:`3669`,
+   :pull:`3670`, :pull:`3671`, :pull:`3672`, :pull:`3742`, :pull:`3746`)
+
+#. `@lbdreyer`_ and `@pp-mo`_ overhauled the handling of dimensional
+   metadata to remove duplication. (:pull:`3422`, :pull:`3551`)
+
+#. `@trexfeathers`_ simplified the standard license header for all files, which
+   removes the need to repeatedly update year numbers in the header.
+   (:pull:`3489`)
+
+#. `@stephenworsley`_ changed the numerical values in tests involving the
+   Robinson projection due to improvements made in
+   `Proj`_. (:pull:`3762`) (see also `Proj#1292`_ and `Proj#2151`_)
+
+#. `@stephenworsley`_ changed tests to account for more detailed descriptions of
+   projections in `GDAL`_. (:pull:`3762`) (see also `GDAL#1185`_)
+
+#. `@stephenworsley`_ changed tests to account for `GDAL`_ now saving fill values
+   for data without masked points. (:pull:`3762`)
+
+#. `@trexfeathers`_ changed every graphics test that includes `Cartopy's coastlines`_
+   to account for new adaptive coastline scaling. (:pull:`3762`)
+   (see also `Cartopy#1105`_)
+
+#. `@trexfeathers`_ changed graphics tests to account for some new default
+   grid-line spacing in `Cartopy`_. (:pull:`3762`) (see also `Cartopy#1117`_)
+
+#. `@trexfeathers`_ added additional acceptable graphics test targets to account
+   for very minor changes in `matplotlib`_ version ``3.3`` (colormaps, fonts and
+   axes borders). (:pull:`3762`)
+
+#. `@rcomer`_ corrected the `matplotlib`_ backend in Iris tests to ignore
+   :obj:`matplotlib.rcdefaults`, instead the tests will **always** use ``agg``.
+   (:pull:`3846`)
+
+#. `@bjlittle`_ migrated the `black`_ support from ``19.10b0`` to ``20.8b1``.
+   (:pull:`3866`)
+
+#. `@lbdreyer`_ updated the CF standard name table to the latest version: `v75`_.
+   (:pull:`3867`)
+
+#. `@bjlittle`_ added :pep:`517` and :pep:`518` support for building and
+   installing Iris, in particular to handle the `PyKE`_ package dependency.
+   (:pull:`3812`)
+
+#. `@bjlittle`_ added metadata support for comparing :attr:`~iris.cube.Cube.attributes`
+   dictionaries that contain `numpy`_ arrays using `xxHash`_, an extremely fast
+   non-cryptographic hash algorithm, running at RAM speed limits.
+
+#. `@bjlittle`_ added the ``iris.tests.assertDictEqual`` method to override
+   :meth:`unittest.TestCase.assertDictEqual` in order to cope with testing
+   metadata :attr:`~iris.cube.Cube.attributes` dictionary comparison where
+   the value of a key may be a `numpy`_ array. (:pull:`3785`)
+
+#. `@bjlittle`_ added the :func:`~iris.config.get_logger` function for creating
+   a generic :class:`logging.Logger` with a :class:`logging.StreamHandler` and
+   custom :class:`logging.Formatter`. (:pull:`3785`)
+
+#. `@owena11`_ identified and optimised a bottleneck in ``FieldsFile`` header
+   loading due to the use of :func:`numpy.fromfile`. (:pull:`3791`)
+
+#. `@znicholls`_ added a test for plotting with the label being taken from the unit's symbol,
+   see :meth:`~iris.tests.test_quickplot.TestLabels.test_pcolormesh_str_symbol` (:pull:`3902`).
+
+#. `@znicholls`_ made :func:`~iris.tests.idiff.step_over_diffs` robust to hyphens (``-``) in
+   the input path (i.e. the ``result_dir`` argument) (:pull:`3902`).
+
+#. `@bjlittle`_ migrated the CIaaS from `travis-ci`_ to `cirrus-ci`_, and removed `stickler-ci`_
+   support. (:pull:`3928`)
+
+#. `@bjlittle`_ introduced `nox`_ as a common and easy entry-point for test automation.
+   It can be used both from `cirrus-ci`_ in the cloud, and locally by the developer to
+   run the Iris tests, the doc-tests, the gallery doc-tests, and lint Iris
+   with `flake8`_ and `black`_. (:pull:`3928`)
+
+.. _Read the Docs: https://scitools-iris.readthedocs.io/en/latest/
+.. _CF units rules: https://cfconventions.org/Data/cf-conventions/cf-conventions-1.8/cf-conventions.html#units
+.. _CF Ancillary Data: https://cfconventions.org/Data/cf-conventions/cf-conventions-1.8/cf-conventions.html#ancillary-data
+.. _Quality Flags: https://cfconventions.org/Data/cf-conventions/cf-conventions-1.8/cf-conventions.html#flags
+.. _iris-grib: https://github.com/SciTools/iris-grib
+.. _Cartopy: https://github.com/SciTools/cartopy
+.. _Cartopy's coastlines: https://scitools.org.uk/cartopy/docs/latest/matplotlib/geoaxes.html?highlight=coastlines#cartopy.mpl.geoaxes.GeoAxes.coastlines
+.. _Cartopy#1105: https://github.com/SciTools/cartopy/pull/1105
+.. _Cartopy#1117: https://github.com/SciTools/cartopy/pull/1117
+.. _Dask: https://github.com/dask/dask
+.. _Proj: https://github.com/OSGeo/PROJ
+.. _black: https://black.readthedocs.io/en/stable/
+.. _Proj#1292: https://github.com/OSGeo/PROJ/pull/1292
+.. _Proj#2151: https://github.com/OSGeo/PROJ/pull/2151
+.. _GDAL: https://github.com/OSGeo/gdal
+.. _GDAL#1185: https://github.com/OSGeo/gdal/pull/1185
+.. _@MoseleyS: https://github.com/MoseleyS
+.. _@stephenworsley: https://github.com/stephenworsley
+.. _@pp-mo: https://github.com/pp-mo
+.. _@abooton: https://github.com/abooton
+.. _@bouweandela: https://github.com/bouweandela
+.. _@bjlittle: https://github.com/bjlittle
+.. _@trexfeathers: https://github.com/trexfeathers
+.. _@jonseddon: https://github.com/jonseddon
+.. _@tkknight: https://github.com/tkknight
+.. _@lbdreyer: https://github.com/lbdreyer
+.. _@SimonPeatman: https://github.com/SimonPeatman
+.. _@TomekTrzeciak: https://github.com/TomekTrzeciak
+.. _@rcomer: https://github.com/rcomer
+.. _@jvegasbsc: https://github.com/jvegasbsc
+.. _@zklaus: https://github.com/zklaus
+.. _@znicholls: https://github.com/znicholls
+.. _ESMValTool: https://github.com/ESMValGroup/ESMValTool
+.. _v75: https://cfconventions.org/Data/cf-standard-names/75/build/cf-standard-name-table.html
+.. _sphinx-panels: https://sphinx-panels.readthedocs.io/en/latest/
+.. _logging: https://docs.python.org/3/library/logging.html
+.. _numpy: https://github.com/numpy/numpy
+.. _xxHash: https://github.com/Cyan4973/xxHash
+.. _PyKE: https://pypi.org/project/scitools-pyke/
+.. _@owena11: https://github.com/owena11
+.. _GitHub: https://github.com/SciTools/iris/issues/new/choose
+.. _readthedocs: https://readthedocs.org/
+.. _CF Conventions and Metadata: https://cfconventions.org/
+.. _flake8: https://flake8.pycqa.org/en/stable/
+.. _nox: https://nox.thea.codes/en/stable/
+.. _Title Case Capitalization: https://apastyle.apa.org/style-grammar-guidelines/capitalization/title-case
+.. _travis-ci: https://travis-ci.org/github/SciTools/iris
+.. _stickler-ci: https://stickler-ci.com/
+.. _@jamesp: https://github.com/jamesp
diff --git a/docs/iris/src/whatsnew/3.0.rst b/docs/iris/src/whatsnew/3.0.rst
index 399325add5..7fdc2e3400 100644
--- a/docs/iris/src/whatsnew/3.0.rst
+++ b/docs/iris/src/whatsnew/3.0.rst
@@ -43,204 +43,204 @@ This document explains the changes made to Iris for this release
 📢 Announcements
 ================
 
-* Congratulations to `@bouweandela`_, `@jvegasbsc`_, and `@zklaus`_ who
-  recently became Iris core developers. They bring a wealth of expertise to the
-  team, and are using Iris to underpin `ESMValTool`_ - "*A community diagnostic
-  and performance metrics tool for routine evaluation of Earth system models
-  in CMIP*". Welcome aboard! 🎉
+#. Congratulations to `@bouweandela`_, `@jvegasbsc`_, and `@zklaus`_ who
+   recently became Iris core developers. They bring a wealth of expertise to the
+   team, and are using Iris to underpin `ESMValTool`_ - "*A community diagnostic
+   and performance metrics tool for routine evaluation of Earth system models
+   in CMIP*". Welcome aboard! 🎉
 
-* Congratulations also goes to `@jonseddon`_ who recently became an Iris core
-  developer. We look forward to seeing more of your awesome contributions! 🎉
+#. Congratulations also goes to `@jonseddon`_ who recently became an Iris core
+   developer. We look forward to seeing more of your awesome contributions! 🎉
 
 
 ✨ Features
 ===========
 
-* `@MoseleyS`_ greatly enhanced  the :mod:`~iris.fileformats.nimrod`
-  module to provide richer meta-data translation when loading ``Nimrod`` data
-  into cubes. This covers most known operational use-cases. (:pull:`3647`)
-
-* `@stephenworsley`_ improved the handling of
-  :class:`iris.coords.CellMeasure`\ s in the :class:`~iris.cube.Cube`
-  statistical operations :meth:`~iris.cube.Cube.collapsed`,
-  :meth:`~iris.cube.Cube.aggregated_by` and
-  :meth:`~iris.cube.Cube.rolling_window`. These previously removed every
-  :class:`~iris.coords.CellMeasure` attached to the cube.  Now, a
-  :class:`~iris.coords.CellMeasure` will only be removed if it is associated
-  with an axis over which the statistic is being run. (:pull:`3549`)
-
-* `@stephenworsley`_, `@pp-mo`_ and `@abooton`_ added support for
-  `CF Ancillary Data`_ variables.  These are created as
-  :class:`iris.coords.AncillaryVariable`, and appear as components of cubes
-  much like :class:`~iris.coords.AuxCoord`\ s, with the new
-  :class:`~iris.cube.Cube` methods
-  :meth:`~iris.cube.Cube.add_ancillary_variable`,
-  :meth:`~iris.cube.Cube.remove_ancillary_variable`,
-  :meth:`~iris.cube.Cube.ancillary_variable`,
-  :meth:`~iris.cube.Cube.ancillary_variables` and
-  :meth:`~iris.cube.Cube.ancillary_variable_dims`.
-  They are loaded from and saved to NetCDF-CF files.  Special support for
-  `Quality Flags`_ is also provided, to ensure they load and save with
-  appropriate units. (:pull:`3800`)
-
-* `@bouweandela`_ implemented lazy regridding for the
-  :class:`~iris.analysis.Linear`, :class:`~iris.analysis.Nearest`, and
-  :class:`~iris.analysis.AreaWeighted` regridding schemes. (:pull:`3701`)
-
-* `@bjlittle`_ added `logging`_ support within :mod:`iris.analysis.maths`,
-  :mod:`iris.common.metadata`, and :mod:`iris.common.resolve`. Each module
-  defines a :class:`logging.Logger` instance called ``logger`` with a default
-  ``level`` of ``INFO``. To enable ``DEBUG`` logging use
-  ``logger.setLevel("DEBUG")``. (:pull:`3785`)
-
-* `@bjlittle`_ added the :mod:`iris.common.resolve` module, which provides
-  infrastructure to support the analysis, identification and combination
-  of metadata common between two :class:`~iris.cube.Cube` operands into a
-  single resultant :class:`~iris.cube.Cube` that will be auto-transposed,
-  and with the appropriate broadcast shape. (:pull:`3785`)
-
-* `@bjlittle`_ added the :ref:`common metadata API <metadata>`, which provides
-  a unified treatment of metadata across Iris, and allows users to easily
-  manage and manipulate their metadata in a consistent way. (:pull:`3785`)
-
-* `@bjlittle`_ added :ref:`lenient metadata <lenient metadata>` support, to
-  allow users to control **strict** or **lenient** metadata equivalence,
-  difference and combination. (:pull:`3785`)
-
-* `@bjlittle`_ added :ref:`lenient cube maths <lenient maths>` support and
-  resolved several long standing major issues with cube arithmetic regarding
-  a more robust treatment of cube broadcasting, cube dimension auto-transposition,
-  and preservation of common metadata and coordinates during cube math operations.
-  Resolves :issue:`1887`, :issue:`2765`, and :issue:`3478`. (:pull:`3785`)
-
-* `@pp-mo`_ and `@TomekTrzeciak`_ enhanced :meth:`~iris.cube.Cube.collapse` to allow a 1-D weights array when
-  collapsing over a single dimension.
-  Previously, the weights had to be the same shape as the whole cube, which could cost a lot of memory in some cases.
-  The 1-D form is supported by most weighted array statistics (such as :meth:`np.average`), so this now works
-  with the corresponding Iris schemes (in that case, :const:`~iris.analysis.MEAN`).  (:pull:`3943`)
+#. `@MoseleyS`_ greatly enhanced  the :mod:`~iris.fileformats.nimrod`
+   module to provide richer meta-data translation when loading ``Nimrod`` data
+   into cubes. This covers most known operational use-cases. (:pull:`3647`)
+
+#. `@stephenworsley`_ improved the handling of
+   :class:`iris.coords.CellMeasure`\ s in the :class:`~iris.cube.Cube`
+   statistical operations :meth:`~iris.cube.Cube.collapsed`,
+   :meth:`~iris.cube.Cube.aggregated_by` and
+   :meth:`~iris.cube.Cube.rolling_window`. These previously removed every
+   :class:`~iris.coords.CellMeasure` attached to the cube.  Now, a
+   :class:`~iris.coords.CellMeasure` will only be removed if it is associated
+   with an axis over which the statistic is being run. (:pull:`3549`)
+
+#. `@stephenworsley`_, `@pp-mo`_ and `@abooton`_ added support for
+   `CF Ancillary Data`_ variables.  These are created as
+   :class:`iris.coords.AncillaryVariable`, and appear as components of cubes
+   much like :class:`~iris.coords.AuxCoord`\ s, with the new
+   :class:`~iris.cube.Cube` methods
+   :meth:`~iris.cube.Cube.add_ancillary_variable`,
+   :meth:`~iris.cube.Cube.remove_ancillary_variable`,
+   :meth:`~iris.cube.Cube.ancillary_variable`,
+   :meth:`~iris.cube.Cube.ancillary_variables` and
+   :meth:`~iris.cube.Cube.ancillary_variable_dims`.
+   They are loaded from and saved to NetCDF-CF files.  Special support for
+   `Quality Flags`_ is also provided, to ensure they load and save with
+   appropriate units. (:pull:`3800`)
+
+#. `@bouweandela`_ implemented lazy regridding for the
+   :class:`~iris.analysis.Linear`, :class:`~iris.analysis.Nearest`, and
+   :class:`~iris.analysis.AreaWeighted` regridding schemes. (:pull:`3701`)
+
+#. `@bjlittle`_ added `logging`_ support within :mod:`iris.analysis.maths`,
+   :mod:`iris.common.metadata`, and :mod:`iris.common.resolve`. Each module
+   defines a :class:`logging.Logger` instance called ``logger`` with a default
+   ``level`` of ``INFO``. To enable ``DEBUG`` logging use
+   ``logger.setLevel("DEBUG")``. (:pull:`3785`)
+
+#. `@bjlittle`_ added the :mod:`iris.common.resolve` module, which provides
+   infrastructure to support the analysis, identification and combination
+   of metadata common between two :class:`~iris.cube.Cube` operands into a
+   single resultant :class:`~iris.cube.Cube` that will be auto-transposed,
+   and with the appropriate broadcast shape. (:pull:`3785`)
+
+#. `@bjlittle`_ added the :ref:`common metadata API <metadata>`, which provides
+   a unified treatment of metadata across Iris, and allows users to easily
+   manage and manipulate their metadata in a consistent way. (:pull:`3785`)
+
+#. `@bjlittle`_ added :ref:`lenient metadata <lenient metadata>` support, to
+   allow users to control **strict** or **lenient** metadata equivalence,
+   difference and combination. (:pull:`3785`)
+
+#. `@bjlittle`_ added :ref:`lenient cube maths <lenient maths>` support and
+   resolved several long standing major issues with cube arithmetic regarding
+   a more robust treatment of cube broadcasting, cube dimension auto-transposition,
+   and preservation of common metadata and coordinates during cube math operations.
+   Resolves :issue:`1887`, :issue:`2765`, and :issue:`3478`. (:pull:`3785`)
+
+#. `@pp-mo`_ and `@TomekTrzeciak`_ enhanced :meth:`~iris.cube.Cube.collapse` to allow a 1-D weights array when
+   collapsing over a single dimension.
+   Previously, the weights had to be the same shape as the whole cube, which could cost a lot of memory in some cases.
+   The 1-D form is supported by most weighted array statistics (such as :meth:`np.average`), so this now works
+   with the corresponding Iris schemes (in that case, :const:`~iris.analysis.MEAN`).  (:pull:`3943`)
 
 
 🐛 Bugs Fixed
 =============
 
-* `@stephenworsley`_ fixed :meth:`~iris.cube.Cube.remove_coord` to now also
-  remove derived coordinates by removing aux_factories. (:pull:`3641`)
-
-* `@jonseddon`_ fixed ``isinstance(cube, collections.Iterable)`` to now behave
-  as expected if a :class:`~iris.cube.Cube` is iterated over, while also
-  ensuring that ``TypeError`` is still raised. (Fixed by setting the
-  ``__iter__()`` method in :class:`~iris.cube.Cube` to ``None``).
-  (:pull:`3656`)
-
-* `@stephenworsley`_ enabled cube concatenation along an axis shared by cell
-  measures; these cell measures are now concatenated together in the resulting
-  cube. Such a scenario would previously cause concatenation to inappropriately
-  fail. (:pull:`3566`)
-
-* `@stephenworsley`_ newly included :class:`~iris.coords.CellMeasure`\ s in
-  :class:`~iris.cube.Cube` copy operations. Previously copying a
-  :class:`~iris.cube.Cube` would ignore any attached
-  :class:`~iris.coords.CellMeasure`. (:pull:`3546`)
-
-* `@bjlittle`_ set a :class:`~iris.coords.CellMeasure`'s
-  ``measure`` attribute to have a default value of ``area``.
-  Previously, the ``measure`` was provided as a keyword argument to
-  :class:`~iris.coords.CellMeasure` with a default value of ``None``, which
-  caused a ``TypeError`` when no ``measure`` was provided, since ``area`` or
-  ``volume`` are the only accepted values. (:pull:`3533`)
-
-* `@trexfeathers`_ set **all** plot types in :mod:`iris.plot` to now use
-  `matplotlib.dates.date2num`_ to format date/time coordinates for use on a plot
-  axis (previously :meth:`~iris.plot.pcolor` and :meth:`~iris.plot.pcolormesh`
-  did not include this behaviour). (:pull:`3762`)
-
-* `@trexfeathers`_ changed date/time axis labels in :mod:`iris.quickplot` to
-  now **always** be based on the ``epoch`` used in `matplotlib.dates.date2num`_
-  (previously would take the unit from a time coordinate, if present, even
-  though the coordinate's value had been changed via ``date2num``).
-  (:pull:`3762`)
-
-* `@pp-mo`_ newly included attributes of cell measures in NETCDF-CF
-  file loading; they were previously being discarded. They are now available on
-  the :class:`~iris.coords.CellMeasure` in the loaded :class:`~iris.cube.Cube`.
-  (:pull:`3800`)
-
-* `@pp-mo`_ fixed the netcdf loader to now handle any grid-mapping
-  variables with missing ``false_easting`` and ``false_northing`` properties,
-  which was previously failing for some coordinate systems. See :issue:`3629`.
-  (:pull:`3804`)
-
-* `@stephenworsley`_ changed the way tick labels are assigned from string coords.
-  Previously, the first tick label would occasionally be duplicated. This also
-  removes the use of Matplotlib's deprecated ``IndexFormatter``. (:pull:`3857`)
-
-* `@znicholls`_ fixed :meth:`~iris.quickplot._title` to only check 
-  ``units.is_time_reference`` if the ``units`` symbol is not used. (:pull:`3902`)
-
-* `@rcomer`_ fixed a bug whereby numpy array type attributes on a cube's 
-  coordinates could prevent printing it.  See :issue:`3921`.  (:pull:`3922`)
+#. `@stephenworsley`_ fixed :meth:`~iris.cube.Cube.remove_coord` to now also
+   remove derived coordinates by removing aux_factories. (:pull:`3641`)
+
+#. `@jonseddon`_ fixed ``isinstance(cube, collections.Iterable)`` to now behave
+   as expected if a :class:`~iris.cube.Cube` is iterated over, while also
+   ensuring that ``TypeError`` is still raised. (Fixed by setting the
+   ``__iter__()`` method in :class:`~iris.cube.Cube` to ``None``).
+   (:pull:`3656`)
+
+#. `@stephenworsley`_ enabled cube concatenation along an axis shared by cell
+   measures; these cell measures are now concatenated together in the resulting
+   cube. Such a scenario would previously cause concatenation to inappropriately
+   fail. (:pull:`3566`)
+
+#. `@stephenworsley`_ newly included :class:`~iris.coords.CellMeasure`\ s in
+   :class:`~iris.cube.Cube` copy operations. Previously copying a
+   :class:`~iris.cube.Cube` would ignore any attached
+   :class:`~iris.coords.CellMeasure`. (:pull:`3546`)
+
+#. `@bjlittle`_ set a :class:`~iris.coords.CellMeasure`'s
+   ``measure`` attribute to have a default value of ``area``.
+   Previously, the ``measure`` was provided as a keyword argument to
+   :class:`~iris.coords.CellMeasure` with a default value of ``None``, which
+   caused a ``TypeError`` when no ``measure`` was provided, since ``area`` or
+   ``volume`` are the only accepted values. (:pull:`3533`)
+
+#. `@trexfeathers`_ set **all** plot types in :mod:`iris.plot` to now use
+   :obj:`matplotlib.dates.date2num` to format date/time coordinates for use on a plot
+   axis (previously :meth:`~iris.plot.pcolor` and :meth:`~iris.plot.pcolormesh`
+   did not include this behaviour). (:pull:`3762`)
+
+#. `@trexfeathers`_ changed date/time axis labels in :mod:`iris.quickplot` to
+   now **always** be based on the ``epoch`` used in :obj:`matplotlib.dates.date2num`
+   (previously would take the unit from a time coordinate, if present, even
+   though the coordinate's value had been changed via ``date2num``).
+   (:pull:`3762`)
+
+#. `@pp-mo`_ newly included attributes of cell measures in NETCDF-CF
+   file loading; they were previously being discarded. They are now available on
+   the :class:`~iris.coords.CellMeasure` in the loaded :class:`~iris.cube.Cube`.
+   (:pull:`3800`)
+
+#. `@pp-mo`_ fixed the netcdf loader to now handle any grid-mapping
+   variables with missing ``false_easting`` and ``false_northing`` properties,
+   which was previously failing for some coordinate systems. See :issue:`3629`.
+   (:pull:`3804`)
+
+#. `@stephenworsley`_ changed the way tick labels are assigned from string coords.
+   Previously, the first tick label would occasionally be duplicated. This also
+   removes the use of the deprecated `matplotlib`_ ``IndexFormatter``. (:pull:`3857`)
+
+#. `@znicholls`_ fixed :meth:`~iris.quickplot._title` to only check
+   ``units.is_time_reference`` if the ``units`` symbol is not used. (:pull:`3902`)
+
+#. `@rcomer`_ fixed a bug whereby numpy array type attributes on a cube's
+   coordinates could prevent printing it.  See :issue:`3921`.  (:pull:`3922`)
 
 .. _whatsnew 3.0 changes:
 
 💣 Incompatible Changes
 =======================
 
-* `@pp-mo`_ rationalised :class:`~iris.cube.CubeList` extraction
-  methods:
-
-  The former method ``iris.cube.CubeList.extract_strict``, and the ``strict``
-  keyword of the :meth:`~iris.cube.CubeList.extract` method have been removed,
-  and are replaced by the new routines :meth:`~iris.cube.CubeList.extract_cube`
-  and :meth:`~iris.cube.CubeList.extract_cubes`.
-  The new routines perform the same operation, but in a style more like other
-  ``Iris`` functions such as :meth:`~iris.load_cube` and :meth:`~iris.load_cubes`.
-  Unlike ``strict`` extraction, the type of return value is now completely
-  consistent : :meth:`~iris.cube.CubeList.extract_cube` always returns a
-  :class:`~iris.cube.Cube`, and :meth:`~iris.cube.CubeList.extract_cubes`
-  always returns an :class:`iris.cube.CubeList` of a length equal to the
-  number of constraints. (:pull:`3715`)
-
-* `@pp-mo`_ removed the former function
-  ``iris.analysis.coord_comparison``. (:pull:`3562`)
-
-* `@bjlittle`_ moved the
-  :func:`iris.experimental.equalise_cubes.equalise_attributes` function from
-  the :mod:`iris.experimental` module into the :mod:`iris.util` module.  Please
-  use the :func:`iris.util.equalise_attributes` function instead.
-  (:pull:`3527`)
-
-* `@bjlittle`_ removed the module ``iris.experimental.concatenate``. In
-  ``v1.6.0`` the experimental ``concatenate`` functionality was moved to the
-  :meth:`iris.cube.CubeList.concatenate` method.  Since then, calling the
-  :func:`iris.experimental.concatenate.concatenate` function raised an
-  exception. (:pull:`3523`)
-
-* `@stephenworsley`_ changed the default units of :class:`~iris.coords.DimCoord` 
-  and :class:`~iris.coords.AuxCoord` from `"1"` to `"unknown"`.  (:pull:`3795`)
-
-* `@stephenworsley`_ changed Iris objects loaded from NetCDF-CF files to have
-  ``units='unknown'`` where the corresponding NetCDF variable has no ``units``
-  property. Previously these cases defaulted to ``units='1'``.
-  This affects loading of coordinates whose file variable has no "units"
-  attribute (not valid, under `CF units rules`_):  These will now have units
-  of `"unknown"`, rather than `"1"`, which **may prevent the creation of
-  a hybrid vertical coordinate**.  While these cases used to "work", this was
-  never really correct behaviour. (:pull:`3795`)
-
-* `@SimonPeatman`_ added attribute ``var_name`` to coordinates created by the
-  :func:`iris.analysis.trajectory.interpolate` function.  This prevents
-  duplicate coordinate errors in certain circumstances. (:pull:`3718`)
-
-* `@bjlittle`_ aligned the :func:`iris.analysis.maths.apply_ufunc` with the
-  rest of the :mod:`iris.analysis.maths` API by changing its keyword argument
-  from ``other_cube`` to ``other``. (:pull:`3785`)
-
-* `@bjlittle`_ changed the :meth:`iris.analysis.maths.IFunc.__call__` to ignore
-  any surplus ``other`` keyword argument for a ``data_func`` that requires
-  **only one** argument. This aligns the behaviour of
-  :meth:`iris.analysis.maths.IFunc.__call__` with
-  :func:`~iris.analysis.maths.apply_ufunc`. Previously a ``ValueError``
-  exception was raised. (:pull:`3785`)
+#. `@pp-mo`_ rationalised :class:`~iris.cube.CubeList` extraction
+   methods:
+
+   The former method ``iris.cube.CubeList.extract_strict``, and the ``strict``
+   keyword of the :meth:`~iris.cube.CubeList.extract` method have been removed,
+   and are replaced by the new routines :meth:`~iris.cube.CubeList.extract_cube`
+   and :meth:`~iris.cube.CubeList.extract_cubes`.
+   The new routines perform the same operation, but in a style more like other
+   ``Iris`` functions such as :meth:`~iris.load_cube` and :meth:`~iris.load_cubes`.
+   Unlike ``strict`` extraction, the type of return value is now completely
+   consistent : :meth:`~iris.cube.CubeList.extract_cube` always returns a
+   :class:`~iris.cube.Cube`, and :meth:`~iris.cube.CubeList.extract_cubes`
+   always returns an :class:`iris.cube.CubeList` of a length equal to the
+   number of constraints. (:pull:`3715`)
+
+#. `@pp-mo`_ removed the former function
+   ``iris.analysis.coord_comparison``. (:pull:`3562`)
+
+#. `@bjlittle`_ moved the
+   :func:`iris.experimental.equalise_cubes.equalise_attributes` function from
+   the :mod:`iris.experimental` module into the :mod:`iris.util` module.  Please
+   use the :func:`iris.util.equalise_attributes` function instead.
+   (:pull:`3527`)
+
+#. `@bjlittle`_ removed the module ``iris.experimental.concatenate``. In
+   ``v1.6.0`` the experimental ``concatenate`` functionality was moved to the
+   :meth:`iris.cube.CubeList.concatenate` method.  Since then, calling the
+   :func:`iris.experimental.concatenate.concatenate` function raised an
+   exception. (:pull:`3523`)
+
+#. `@stephenworsley`_ changed the default units of :class:`~iris.coords.DimCoord`
+   and :class:`~iris.coords.AuxCoord` from `"1"` to `"unknown"`.  (:pull:`3795`)
+
+#. `@stephenworsley`_ changed Iris objects loaded from NetCDF-CF files to have
+   ``units='unknown'`` where the corresponding NetCDF variable has no ``units``
+   property. Previously these cases defaulted to ``units='1'``.
+   This affects loading of coordinates whose file variable has no "units"
+   attribute (not valid, under `CF units rules`_):  These will now have units
+   of `"unknown"`, rather than `"1"`, which **may prevent the creation of
+   a hybrid vertical coordinate**.  While these cases used to "work", this was
+   never really correct behaviour. (:pull:`3795`)
+
+#. `@SimonPeatman`_ added attribute ``var_name`` to coordinates created by the
+   :func:`iris.analysis.trajectory.interpolate` function.  This prevents
+   duplicate coordinate errors in certain circumstances. (:pull:`3718`)
+
+#. `@bjlittle`_ aligned the :func:`iris.analysis.maths.apply_ufunc` with the
+   rest of the :mod:`iris.analysis.maths` API by changing its keyword argument
+   from ``other_cube`` to ``other``. (:pull:`3785`)
+
+#. `@bjlittle`_ changed the :meth:`iris.analysis.maths.IFunc.__call__` to ignore
+   any surplus ``other`` keyword argument for a ``data_func`` that requires
+   **only one** argument. This aligns the behaviour of
+   :meth:`iris.analysis.maths.IFunc.__call__` with
+   :func:`~iris.analysis.maths.apply_ufunc`. Previously a ``ValueError``
+   exception was raised. (:pull:`3785`)
 
 
 .. _whatsnew 3.0 deprecations:
@@ -248,48 +248,48 @@ This document explains the changes made to Iris for this release
 🔥 Deprecations
 ===============
 
-* `@stephenworsley`_ removed the deprecated :class:`iris.Future` flags
-  ``cell_date_time_objects``, ``netcdf_promote``, ``netcdf_no_unlimited`` and
-  ``clip_latitudes``. (:pull:`3459`)
+#. `@stephenworsley`_ removed the deprecated :class:`iris.Future` flags
+   ``cell_date_time_objects``, ``netcdf_promote``, ``netcdf_no_unlimited`` and
+   ``clip_latitudes``. (:pull:`3459`)
 
-* `@stephenworsley`_ changed :attr:`iris.fileformats.pp.PPField.lbproc` to be an
-  ``int``. The deprecated attributes ``flag1``, ``flag2`` etc. have been
-  removed from it. (:pull:`3461`)
+#. `@stephenworsley`_ changed :attr:`iris.fileformats.pp.PPField.lbproc` to be an
+   ``int``. The deprecated attributes ``flag1``, ``flag2`` etc. have been
+   removed from it. (:pull:`3461`)
 
-* `@bjlittle`_ deprecated :func:`~iris.util.as_compatible_shape` in preference
-  for :class:`~iris.common.resolve.Resolve` e.g., ``Resolve(src, tgt)(tgt.core_data())``.
-  The :func:`~iris.util.as_compatible_shape` function will be removed in a future
-  release of Iris. (:pull:`3892`)
+#. `@bjlittle`_ deprecated :func:`~iris.util.as_compatible_shape` in preference
+   for :class:`~iris.common.resolve.Resolve` e.g., ``Resolve(src, tgt)(tgt.core_data())``.
+   The :func:`~iris.util.as_compatible_shape` function will be removed in a future
+   release of Iris. (:pull:`3892`)
 
 
 🔗 Dependencies
 ===============
 
-* `@stephenworsley`_, `@trexfeathers`_ and `@bjlittle`_ removed ``Python2``
-  support, modernising the codebase by switching to exclusive ``Python3``
-  support. (:pull:`3513`)
+#. `@stephenworsley`_, `@trexfeathers`_ and `@bjlittle`_ removed ``Python2``
+   support, modernising the codebase by switching to exclusive ``Python3``
+   support. (:pull:`3513`)
 
-* `@bjlittle`_ improved the developer set up process. Configuring Iris and
-  :ref:`installing_from_source` as a developer with all the required package
-  dependencies is now easier with our curated conda environment YAML files.
-  (:pull:`3812`)
+#. `@bjlittle`_ improved the developer set up process. Configuring Iris and
+   :ref:`installing_from_source` as a developer with all the required package
+   dependencies is now easier with our curated conda environment YAML files.
+   (:pull:`3812`)
 
-* `@stephenworsley`_ pinned Iris to require `Dask`_ ``>=2.0``. (:pull:`3460`)
+#. `@stephenworsley`_ pinned Iris to require `Dask`_ ``>=2.0``. (:pull:`3460`)
 
-* `@stephenworsley`_ and `@trexfeathers`_ pinned Iris to require
-  `Cartopy`_ ``>=0.18``, in order to remain compatible with the latest version
-  of `Matplotlib`_. (:pull:`3762`)
+#. `@stephenworsley`_ and `@trexfeathers`_ pinned Iris to require
+   `Cartopy`_ ``>=0.18``, in order to remain compatible with the latest version
+   of `matplotlib`_. (:pull:`3762`)
 
-* `@bjlittle`_ unpinned Iris to use the latest version of `Matplotlib`_.
-  Supporting ``Iris`` for both ``Python2`` and ``Python3`` had resulted in
-  pinning our dependency on `Matplotlib`_ at ``v2.x``.  But this is no longer
-  necessary now that ``Python2`` support has been dropped. (:pull:`3468`)
+#. `@bjlittle`_ unpinned Iris to use the latest version of `matplotlib`_.
+   Supporting ``Iris`` for both ``Python2`` and ``Python3`` had resulted in
+   pinning our dependency on `matplotlib`_ at ``v2.x``.  But this is no longer
+   necessary now that ``Python2`` support has been dropped. (:pull:`3468`)
 
-* `@stephenworsley`_ and `@trexfeathers`_ unpinned Iris to use the latest version
-  of `Proj`_. (:pull:`3762`)
+#. `@stephenworsley`_ and `@trexfeathers`_ unpinned Iris to use the latest version
+   of `Proj`_. (:pull:`3762`)
 
-* `@stephenworsley`_ and `@trexfeathers`_ removed GDAL from the extensions
-  dependency group. We no longer consider it to be an extension. (:pull:`3762`)
+#. `@stephenworsley`_ and `@trexfeathers`_ removed GDAL from the extensions
+   dependency group. We no longer consider it to be an extension. (:pull:`3762`)
 
 
 .. _whatsnew 3.0 docs:
@@ -297,160 +297,162 @@ This document explains the changes made to Iris for this release
 📚 Documentation
 ================
 
-* `@tkknight`_ moved the
-  :ref:`sphx_glr_generated_gallery_oceanography_plot_orca_projection.py`
-  from the general part of the gallery to oceanography. (:pull:`3761`)
+#. `@tkknight`_ moved the
+   :ref:`sphx_glr_generated_gallery_oceanography_plot_orca_projection.py`
+   from the general part of the gallery to oceanography. (:pull:`3761`)
 
-* `@tkknight`_ updated documentation to use a modern sphinx theme and be
-  served from https://scitools-iris.readthedocs.io/en/latest/. (:pull:`3752`)
+#. `@tkknight`_ updated documentation to use a modern sphinx theme and be
+   served from https://scitools-iris.readthedocs.io/en/latest/. (:pull:`3752`)
 
-* `@bjlittle`_ added support for the `black`_ code formatter. This is
-  now automatically checked on GitHub PRs, replacing the older, unittest-based
-  ``iris.tests.test_coding_standards.TestCodeFormat``. Black provides automatic
-  code format correction for most IDEs.  See the new developer guide section on
-  :ref:`code_formatting`. (:pull:`3518`)
+#. `@bjlittle`_ added support for the `black`_ code formatter. This is
+   now automatically checked on GitHub PRs, replacing the older, unittest-based
+   ``iris.tests.test_coding_standards.TestCodeFormat``. Black provides automatic
+   code format correction for most IDEs.  See the new developer guide section on
+   :ref:`code_formatting`. (:pull:`3518`)
 
-* `@tkknight`_ and `@trexfeathers`_ refreshed the :ref:`whats_new_contributions`
-  for the :ref:`iris_whatsnew`. This includes always creating the ``latest``
-  what's new page so it appears on the latest documentation at
-  https://scitools-iris.readthedocs.io/en/latest/whatsnew. This resolves
-  :issue:`2104`, :issue:`3451`, :issue:`3818`, :issue:`3837`.  Also updated the
-  :ref:`iris_development_releases_steps` to follow when making a release.
-  (:pull:`3769`, :pull:`3838`, :pull:`3843`)
+#. `@tkknight`_ and `@trexfeathers`_ refreshed the :ref:`whats_new_contributions`
+   for the :ref:`iris_whatsnew`. This includes always creating the ``latest``
+   what's new page so it appears on the latest documentation at
+   https://scitools-iris.readthedocs.io/en/latest/whatsnew. This resolves
+   :issue:`2104`, :issue:`3451`, :issue:`3818`, :issue:`3837`.  Also updated the
+   :ref:`iris_development_releases_steps` to follow when making a release.
+   (:pull:`3769`, :pull:`3838`, :pull:`3843`)
 
-* `@tkknight`_ enabled the PDF creation of the documentation on the
-  `Read the Docs`_ service. The PDF may be accessed by clicking on the version
-  at the bottom of the side bar, then selecting ``PDF`` from the ``Downloads``
-  section. (:pull:`3765`)
+#. `@tkknight`_ enabled the PDF creation of the documentation on the
+   `Read the Docs`_ service. The PDF may be accessed by clicking on the version
+   at the bottom of the side bar, then selecting ``PDF`` from the ``Downloads``
+   section. (:pull:`3765`)
 
-* `@stephenworsley`_ added a warning to the
-  :func:`iris.analysis.cartography.project` function regarding its behaviour on
-  projections with non-rectangular boundaries. (:pull:`3762`)
+#. `@stephenworsley`_ added a warning to the
+   :func:`iris.analysis.cartography.project` function regarding its behaviour on
+   projections with non-rectangular boundaries. (:pull:`3762`)
 
-* `@stephenworsley`_ added the :ref:`cube_maths_combining_units` section to the
-  user guide to clarify how ``Units`` are handled during cube arithmetic.
-  (:pull:`3803`)
+#. `@stephenworsley`_ added the :ref:`cube_maths_combining_units` section to the
+   user guide to clarify how ``Units`` are handled during cube arithmetic.
+   (:pull:`3803`)
 
-* `@tkknight`_ overhauled the :ref:`developers_guide` including information on
-  getting involved in becoming a contributor and general structure of the
-  guide.  This resolves :issue:`2170`, :issue:`2331`, :issue:`3453`,
-  :issue:`314`, :issue:`2902`. (:pull:`3852`)
+#. `@tkknight`_ overhauled the :ref:`developers_guide` including information on
+   getting involved in becoming a contributor and general structure of the
+   guide.  This resolves :issue:`2170`, :issue:`2331`, :issue:`3453`,
+   :issue:`314`, :issue:`2902`. (:pull:`3852`)
 
-* `@rcomer`_ added argument descriptions to the :class:`~iris.coords.DimCoord`
-  docstring. (:pull:`3681`)
+#. `@rcomer`_ added argument descriptions to the :class:`~iris.coords.DimCoord`
+   docstring. (:pull:`3681`)
 
-* `@tkknight`_ added two url's to be ignored for the ``make linkcheck``.  This
-  will ensure the Iris github project is not repeatedly hit during the
-  linkcheck for issues and pull requests as it can result in connection
-  refused and thus travis-ci_ job failures.  For more information on linkcheck,
-  see :ref:`contributing.documentation.testing`.  (:pull:`3873`)
+#. `@tkknight`_ added two url's to be ignored for the ``make linkcheck``.  This
+   will ensure the Iris github project is not repeatedly hit during the
+   linkcheck for issues and pull requests as it can result in connection
+   refused and thus travis-ci_ job failures.  For more information on linkcheck,
+   see :ref:`contributing.documentation.testing`.  (:pull:`3873`)
 
-* `@tkknight`_ enabled the napolean_ package that is used by sphinx_ to cater
-  for the existing google style docstrings and to also allow for `numpy`_
-  docstrings.  This resolves :issue:`3841`. (:pull:`3871`)
+#. `@tkknight`_ enabled the napolean_ package that is used by sphinx_ to cater
+   for the existing google style docstrings and to also allow for `numpy`_
+   docstrings.  This resolves :issue:`3841`. (:pull:`3871`)
 
-* `@tkknight`_ configured ``sphinx-build`` to promote warnings to errors when
-  building the documentation via ``make html``.  This will minimise technical
-  debt accruing for the documentation.  (:pull:`3877`)
+#. `@tkknight`_ configured ``sphinx-build`` to promote warnings to errors when
+   building the documentation via ``make html``.  This will minimise technical
+   debt accruing for the documentation.  (:pull:`3877`)
 
-* `@tkknight`_ updated :ref:`installing_iris` to include a reference to
-  Windows Subsystem for Linux. (:pull:`3885`)
+#. `@tkknight`_ updated :ref:`installing_iris` to include a reference to
+   Windows Subsystem for Linux. (:pull:`3885`)
 
-* `@tkknight`_ updated the :ref:`iris_docs` homepage to include panels so the
-  links are more visible to users.  This uses the sphinx-panels_ extension.
-  (:pull:`3884`)
+#. `@tkknight`_ updated the :ref:`iris_docs` homepage to include panels so the
+   links are more visible to users.  This uses the sphinx-panels_ extension.
+   (:pull:`3884`)
 
-* `@bjlittle`_ created the :ref:`Further topics <further topics>` section and
-  included documentation for :ref:`metadata`, :ref:`lenient metadata`, and
-  :ref:`lenient maths`. (:pull:`3890`)
+#. `@bjlittle`_ created the :ref:`Further topics <further topics>` section and
+   included documentation for :ref:`metadata`, :ref:`lenient metadata`, and
+   :ref:`lenient maths`. (:pull:`3890`)
 
-* `@jonseddon`_ updated the CF version of the netCDF saver in the 
-  :ref:`saving_iris_cubes` section and in the equivalent function docstring.
-  (:pull:`3925`)
+#. `@jonseddon`_ updated the CF version of the netCDF saver in the
+   :ref:`saving_iris_cubes` section and in the equivalent function docstring.
+   (:pull:`3925`)
 
-* `@bjlittle`_ applied `Title Case Capitalization`_ to the documentation.
-  (:pull:`3940`)
+#. `@bjlittle`_ applied `Title Case Capitalization`_ to the documentation.
+   (:pull:`3940`)
 
 
 💼 Internal
 ===========
 
-* `@pp-mo`_ and `@lbdreyer`_ removed all Iris test dependencies on `iris-grib`_
-  by transferring all relevant content to the `iris-grib`_ repository. (:pull:`3662`,
-  :pull:`3663`, :pull:`3664`, :pull:`3665`, :pull:`3666`, :pull:`3669`,
-  :pull:`3670`, :pull:`3671`, :pull:`3672`, :pull:`3742`, :pull:`3746`)
+#. `@pp-mo`_ and `@lbdreyer`_ removed all Iris test dependencies on `iris-grib`_
+   by transferring all relevant content to the `iris-grib`_ repository. (:pull:`3662`,
+   :pull:`3663`, :pull:`3664`, :pull:`3665`, :pull:`3666`, :pull:`3669`,
+   :pull:`3670`, :pull:`3671`, :pull:`3672`, :pull:`3742`, :pull:`3746`)
 
-* `@lbdreyer`_ and `@pp-mo`_ overhauled the handling of dimensional
-  metadata to remove duplication. (:pull:`3422`, :pull:`3551`)
+#. `@lbdreyer`_ and `@pp-mo`_ overhauled the handling of dimensional
+   metadata to remove duplication. (:pull:`3422`, :pull:`3551`)
 
-* `@trexfeathers`_ simplified the standard license header for all files, which
-  removes the need to repeatedly update year numbers in the header.
-  (:pull:`3489`)
+#. `@trexfeathers`_ simplified the standard license header for all files, which
+   removes the need to repeatedly update year numbers in the header.
+   (:pull:`3489`)
 
-* `@stephenworsley`_ changed the numerical values in tests involving the
-  Robinson projection due to improvements made in
-  `Proj`_. (:pull:`3762`) (see also `Proj#1292`_ and `Proj#2151`_)
+#. `@stephenworsley`_ changed the numerical values in tests involving the
+   Robinson projection due to improvements made in
+   `Proj`_. (:pull:`3762`) (see also `Proj#1292`_ and `Proj#2151`_)
 
-* `@stephenworsley`_ changed tests to account for more detailed descriptions of
-  projections in `GDAL`_. (:pull:`3762`) (see also `GDAL#1185`_)
+#. `@stephenworsley`_ changed tests to account for more detailed descriptions of
+   projections in `GDAL`_. (:pull:`3762`) (see also `GDAL#1185`_)
 
-* `@stephenworsley`_ changed tests to account for `GDAL`_ now saving fill values
-  for data without masked points. (:pull:`3762`)
+#. `@stephenworsley`_ changed tests to account for `GDAL`_ now saving fill values
+   for data without masked points. (:pull:`3762`)
 
-* `@trexfeathers`_ changed every graphics test that includes `Cartopy's coastlines`_
-  to account for new adaptive coastline scaling. (:pull:`3762`)
-  (see also `Cartopy#1105`_)
+#. `@trexfeathers`_ changed every graphics test that includes `Cartopy's coastlines`_
+   to account for new adaptive coastline scaling. (:pull:`3762`)
+   (see also `Cartopy#1105`_)
 
-* `@trexfeathers`_ changed graphics tests to account for some new default
-  grid-line spacing in `Cartopy`_. (:pull:`3762`) (see also `Cartopy#1117`_)
+#. `@trexfeathers`_ changed graphics tests to account for some new default
+   grid-line spacing in `Cartopy`_. (:pull:`3762`) (see also `Cartopy#1117`_)
 
-* `@trexfeathers`_ added additional acceptable graphics test targets to account
-  for very minor changes in `Matplotlib`_ version ``3.3`` (colormaps, fonts and
-  axes borders). (:pull:`3762`)
+#. `@trexfeathers`_ added additional acceptable graphics test targets to account
+   for very minor changes in `matplotlib`_ version ``3.3`` (colormaps, fonts and
+   axes borders). (:pull:`3762`)
 
-* `@rcomer`_ corrected the Matplotlib backend in Iris tests to ignore
-  `matplotlib.rcdefaults`_, instead the tests will **always** use ``agg``.
-  (:pull:`3846`)
+#. `@rcomer`_ corrected the `matplotlib`_ backend in Iris tests to ignore
+   :obj:`matplotlib.rcdefaults`, instead the tests will **always** use ``agg``.
+   (:pull:`3846`)
 
-* `@bjlittle`_ migrated the `black`_ support from ``19.10b0`` to ``20.8b1``.
-  (:pull:`3866`)
+#. `@bjlittle`_ migrated the `black`_ support from ``19.10b0`` to ``20.8b1``.
+   (:pull:`3866`)
 
-* `@lbdreyer`_ updated the CF standard name table to the latest version: `v75`_.
-  (:pull:`3867`)
+#. `@lbdreyer`_ updated the CF standard name table to the latest version: `v75`_.
+   (:pull:`3867`)
 
-* `@bjlittle`_ added :pep:`517` and :pep:`518` support for building and
-  installing Iris, in particular to handle the `PyKE`_ package dependency.
-  (:pull:`3812`)
+#. `@bjlittle`_ added :pep:`517` and :pep:`518` support for building and
+   installing Iris, in particular to handle the `PyKE`_ package dependency.
+   (:pull:`3812`)
 
-* `@bjlittle`_ added metadata support for comparing :attr:`~iris.cube.Cube.attributes`
-  dictionaries that contain `numpy`_ arrays using `xxHash`_, an extremely fast
-  non-cryptographic hash algorithm, running at RAM speed limits.
+#. `@bjlittle`_ added metadata support for comparing :attr:`~iris.cube.Cube.attributes`
+   dictionaries that contain `numpy`_ arrays using `xxHash`_, an extremely fast
+   non-cryptographic hash algorithm, running at RAM speed limits.
 
-* `@bjlittle`_ added the ``iris.tests.assertDictEqual`` method to override
-  :meth:`unittest.TestCase.assertDictEqual` in order to cope with testing
-  metadata :attr:`~iris.cube.Cube.attributes` dictionary comparison where
-  the value of a key may be a `numpy`_ array. (:pull:`3785`)
+#. `@bjlittle`_ added the ``iris.tests.assertDictEqual`` method to override
+   :meth:`unittest.TestCase.assertDictEqual` in order to cope with testing
+   metadata :attr:`~iris.cube.Cube.attributes` dictionary comparison where
+   the value of a key may be a `numpy`_ array. (:pull:`3785`)
 
-* `@bjlittle`_ added the :func:`~iris.config.get_logger` function for creating
-  a generic :class:`logging.Logger` with a :class:`logging.StreamHandler` and
-  custom :class:`logging.Formatter`. (:pull:`3785`)
+#. `@bjlittle`_ added the :func:`~iris.config.get_logger` function for creating
+   a generic :class:`logging.Logger` with a :class:`logging.StreamHandler` and
+   custom :class:`logging.Formatter`. (:pull:`3785`)
 
-* `@owena11`_ identified and optimised a bottleneck in ``FieldsFile`` header
-  loading due to the use of :func:`numpy.fromfile`. (:pull:`3791`)
+#. `@owena11`_ identified and optimised a bottleneck in ``FieldsFile`` header
+   loading due to the use of :func:`numpy.fromfile`. (:pull:`3791`)
 
-* `@znicholls`_ added a test for plotting with the label being taken from the unit's symbol, see :meth:`~iris.tests.test_quickplot.TestLabels.test_pcolormesh_str_symbol` (:pull:`3902`).
+#. `@znicholls`_ added a test for plotting with the label being taken from the unit's symbol,
+   see :meth:`~iris.tests.test_quickplot.TestLabels.test_pcolormesh_str_symbol` (:pull:`3902`).
 
-* `@znicholls`_ made :func:`~iris.tests.idiff.step_over_diffs` robust to hyphens (``-``) in the input path (i.e. the ``result_dir`` argument) (:pull:`3902`).
+#. `@znicholls`_ made :func:`~iris.tests.idiff.step_over_diffs` robust to hyphens (``-``) in
+   the input path (i.e. the ``result_dir`` argument) (:pull:`3902`).
 
-* `@bjlittle`_ migrated the CIaaS from `travis-ci`_ to `cirrus-ci`_, and removed `stickler-ci`_ support. (:pull:`3928`)
+#. `@bjlittle`_ migrated the CIaaS from `travis-ci`_ to `cirrus-ci`_, and removed `stickler-ci`_
+   support. (:pull:`3928`)
 
-* `@bjlittle`_ introduced `nox`_ as a common and easy entry-point for test automation.
-  It can be used both from `cirrus-ci`_ in the cloud, and locally by the developer to
-  run the Iris tests, the doc-tests, the gallery doc-tests, and lint Iris
-  with `flake8`_ and `black`_. (:pull:`3928`)
+#. `@bjlittle`_ introduced `nox`_ as a common and easy entry-point for test automation.
+   It can be used both from `cirrus-ci`_ in the cloud, and locally by the developer to
+   run the Iris tests, the doc-tests, the gallery doc-tests, and lint Iris
+   with `flake8`_ and `black`_. (:pull:`3928`)
 
 .. _Read the Docs: https://scitools-iris.readthedocs.io/en/latest/
-.. _Matplotlib: https://matplotlib.org/
 .. _CF units rules: https://cfconventions.org/Data/cf-conventions/cf-conventions-1.8/cf-conventions.html#units
 .. _CF Ancillary Data: https://cfconventions.org/Data/cf-conventions/cf-conventions-1.8/cf-conventions.html#ancillary-data
 .. _Quality Flags: https://cfconventions.org/Data/cf-conventions/cf-conventions-1.8/cf-conventions.html#flags
@@ -460,7 +462,6 @@ This document explains the changes made to Iris for this release
 .. _Cartopy#1105: https://github.com/SciTools/cartopy/pull/1105
 .. _Cartopy#1117: https://github.com/SciTools/cartopy/pull/1117
 .. _Dask: https://github.com/dask/dask
-.. _matplotlib.dates.date2num: https://matplotlib.org/api/dates_api.html#matplotlib.dates.date2num
 .. _Proj: https://github.com/OSGeo/PROJ
 .. _black: https://black.readthedocs.io/en/stable/
 .. _Proj#1292: https://github.com/OSGeo/PROJ/pull/1292
@@ -490,7 +491,6 @@ This document explains the changes made to Iris for this release
 .. _numpy: https://github.com/numpy/numpy
 .. _xxHash: https://github.com/Cyan4973/xxHash
 .. _PyKE: https://pypi.org/project/scitools-pyke/
-.. _matplotlib.rcdefaults: https://matplotlib.org/3.1.1/api/matplotlib_configuration_api.html?highlight=rcdefaults#matplotlib.rcdefaults
 .. _@owena11: https://github.com/owena11
 .. _GitHub: https://github.com/SciTools/iris/issues/new/choose
 .. _readthedocs: https://readthedocs.org/
diff --git a/docs/iris/src/whatsnew/index.rst b/docs/iris/src/whatsnew/index.rst
index ab5b22b030..a7f152355c 100644
--- a/docs/iris/src/whatsnew/index.rst
+++ b/docs/iris/src/whatsnew/index.rst
@@ -10,6 +10,7 @@ Iris versions.
 .. toctree::
    :maxdepth: 1
 
+   3.0.2.rst
    3.0.1.rst
    3.0.rst
    2.4.rst
diff --git a/lib/iris/__init__.py b/lib/iris/__init__.py
index 0d960c2c30..0034ded236 100644
--- a/lib/iris/__init__.py
+++ b/lib/iris/__init__.py
@@ -106,7 +106,7 @@ def callback(cube, field, filename):
 
 
 # Iris revision.
-__version__ = "3.0.1"
+__version__ = "3.0.2"
 
 # Restrict the names imported when using "from iris import *"
 __all__ = [
diff --git a/lib/iris/tests/test_basic_maths.py b/lib/iris/tests/test_basic_maths.py
index 4b3cde95e4..c4d7b51a06 100644
--- a/lib/iris/tests/test_basic_maths.py
+++ b/lib/iris/tests/test_basic_maths.py
@@ -853,7 +853,7 @@ def setUp(self):
 
     def test_incompatible_dimensions(self):
         data3 = ma.MaskedArray(
-            [[3, 3, 3, 4], [2, 2, 2]], mask=[[0, 1, 0, 0], [0, 1, 1]]
+            [[3, 3, 3, 4], [2, 2, 2, 2]], mask=[[0, 1, 0, 0], [0, 1, 1, 1]]
         )
         with self.assertRaises(ValueError):
             # Incompatible dimensions.