diff --git a/datagateway_api/src/datagateway_api/icat/helpers.py b/datagateway_api/src/datagateway_api/icat/helpers.py
index 285a01d2..3cffcdad 100644
--- a/datagateway_api/src/datagateway_api/icat/helpers.py
+++ b/datagateway_api/src/datagateway_api/icat/helpers.py
@@ -340,21 +340,19 @@ def get_data_with_filters(
     if reader_query.is_query_eligible_for_reader_performance():
         log.info("Query is eligible to be passed as reader acount")
         if reader_query.is_user_authorised_to_see_entity_id(client):
-            # TODO - make reader client reuseable
-            if client_pool:
-                reader_client = get_cached_client(None, client_pool)
-            else:
-                reader_client = ICATClient("datagateway_api")
-            reader_config = Config.config.datagateway_api.use_reader_for_performance
-            login_credentals = {
-                "username": reader_config.reader_username,
-                "password": reader_config.reader_password,
-            }
-            reader_client.login(reader_config.reader_mechanism, login_credentals)
+            reader_client = ReaderQueryHandler.reader_client
             log.info("Query to be executed as reader account")
-            return execute_entity_query(
-                reader_client, entity_type, filters, aggregate=aggregate,
-            )
+            try:
+                results = execute_entity_query(
+                    reader_client, entity_type, filters, aggregate=aggregate,
+                )
+            except ICATSessionError:
+                # re-login as reader and try the query again
+                reader_client = reader_query.create_reader_client()
+                results = execute_entity_query(
+                    reader_client, entity_type, filters, aggregate=aggregate,
+                )
+            return results
         else:
             raise AuthenticationError(
                 "Not authorised to access the"
diff --git a/datagateway_api/src/datagateway_api/icat/reader_query_handler.py b/datagateway_api/src/datagateway_api/icat/reader_query_handler.py
index 9bc08632..f83c22a9 100644
--- a/datagateway_api/src/datagateway_api/icat/reader_query_handler.py
+++ b/datagateway_api/src/datagateway_api/icat/reader_query_handler.py
@@ -3,6 +3,7 @@
 from datagateway_api.src.common.config import Config
 from datagateway_api.src.common.filter_order_handler import FilterOrderHandler
 from datagateway_api.src.datagateway_api.icat.filters import PythonICATWhereFilter
+from datagateway_api.src.datagateway_api.icat.icat_client_pool import ICATClient
 from datagateway_api.src.datagateway_api.icat.query import ICATQuery
 
 log = logging.getLogger()
@@ -13,6 +14,8 @@ class ReaderQueryHandler:
     # TODO - add docstrings
     entity_filter_check = {"Datafile": "dataset.id", "Dataset": "investigation.id"}
     entity_type_check = {"Datafile": "Dataset", "Dataset": "Investigation"}
+    # keep a cached reader_client for faster queries
+    reader_client = None
 
     def __init__(self, entity_type, filters):
         self.entity_type = entity_type
@@ -22,6 +25,21 @@ def __init__(self, entity_type, filters):
             self.entity_type,
         )
         self.reader_query_eligible = self.check_eligibility()
+        self.create_reader_client()
+
+    def create_reader_client(self):
+        log.info("Creating reader_client")
+        ReaderQueryHandler.reader_client = ICATClient("datagateway_api")
+        reader_config = Config.config.datagateway_api.use_reader_for_performance
+        login_credentals = {
+            "username": reader_config.reader_username,
+            "password": reader_config.reader_password,
+        }
+        ReaderQueryHandler.reader_client.login(
+            reader_config.reader_mechanism,
+            login_credentals,
+        )
+        return ReaderQueryHandler.reader_client
 
     def check_eligibility(self):
         reader_config = Config.config.datagateway_api.use_reader_for_performance