diff --git a/core/graph/src/test/java/uk/gov/gchq/gaffer/graph/GraphTest.java b/core/graph/src/test/java/uk/gov/gchq/gaffer/graph/GraphTest.java
index ae42ec9d588..e937196cce2 100644
--- a/core/graph/src/test/java/uk/gov/gchq/gaffer/graph/GraphTest.java
+++ b/core/graph/src/test/java/uk/gov/gchq/gaffer/graph/GraphTest.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2024 Crown Copyright
+ * Copyright 2016-2025 Crown Copyright
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -342,7 +342,7 @@ public void shouldCreateNewContextInstanceWhenExecuteOperation(@Mock final Store
 
     @Test
     public void shouldCreateNewContextInstanceWhenExecuteOutputOperation(@Mock final Store store)
-            throws OperationException, IOException {
+            throws OperationException {
         // Given
         final Schema schema = new Schema();
         given(store.getProperties()).willReturn(new StoreProperties());
@@ -365,7 +365,7 @@ public void shouldCreateNewContextInstanceWhenExecuteOutputOperation(@Mock final
 
     @Test
     public void shouldCreateNewContextInstanceWhenExecuteJob(@Mock final Store store)
-            throws OperationException, IOException {
+            throws OperationException {
         // Given
         final Schema schema = new Schema();
         given(store.getProperties()).willReturn(new StoreProperties());
@@ -1065,7 +1065,7 @@ public void shouldNotSetGraphViewOnOperationWhenOperationIsNotAGet(@Mock final S
     }
 
     @Test
-    public void shouldThrowExceptionIfStoreClassPropertyIsNotSet() throws OperationException {
+    public void shouldThrowExceptionIfStoreClassPropertyIsNotSet() {
         try {
             new Graph.Builder()
                     .config(new GraphConfig.Builder()
@@ -1097,15 +1097,10 @@ public void shouldThrowExceptionIfGraphIdIsMissing() {
     }
 
     @Test
-    public void shouldThrowExceptionIfSchemaIsInvalid() throws OperationException {
+    public void shouldThrowExceptionIfSchemaIsInvalid() {
         final StoreProperties storeProperties = new StoreProperties();
         storeProperties.setStoreClass(TestStoreImpl.class.getName());
-        try {
-            new Graph.Builder()
-                    .config(new GraphConfig.Builder()
-                            .graphId(GRAPH_ID)
-                            .build())
-                    .addSchema(new Schema.Builder()
+        final Schema invalidSchema = new Schema.Builder()
                             .type("int", new TypeDefinition.Builder()
                                     .clazz(Integer.class)
                                     .aggregateFunction(new Sum())
@@ -1126,13 +1121,17 @@ public void shouldThrowExceptionIfSchemaIsInvalid() throws OperationException {
                                     .vertex("string")
                                     .property("p2", "int")
                                     .build())
-                            .build())
+                            .build();
+            final GraphConfig config = new GraphConfig.Builder()
+                            .graphId(GRAPH_ID)
+                            .build();
+        assertThatExceptionOfType(SchemaException.class)
+            .isThrownBy(() -> new Graph.Builder()
+                    .config(config)
+                    .addSchema(invalidSchema)
                     .storeProperties(storeProperties)
-                    .build();
-            fail("exception expected");
-        } catch (final SchemaException e) {
-            assertNotNull(e.getMessage());
-        }
+                    .build())
+                    .withMessageContaining("Schema is not valid");
     }
 
     @Test
@@ -1254,7 +1253,7 @@ private void writeToFile(final String schemaFile, final File dir) throws IOExcep
     }
 
     @Test
-    public void shouldThrowExceptionIfGraphIdIsInvalid(@Mock final StoreProperties properties) throws Exception {
+    void shouldThrowExceptionIfGraphIdIsInvalid(@Mock final StoreProperties properties) {
         try {
             new Graph.Builder()
                     .config(new GraphConfig.Builder()
@@ -1355,8 +1354,7 @@ public void shouldBuildGraphUsingGraphIdAndLookupSchema() throws Exception {
 
     @Test
     public void shouldAddHooksVarArgsAndGetGraphHooks(@Mock final GraphHook graphHook1,
-                                                      @Mock final Log4jLogger graphHook2)
-            throws Exception {
+                                                      @Mock final Log4jLogger graphHook2) {
         // Given
         final StoreProperties storeProperties = new StoreProperties();
         storeProperties.setStoreClass(TestStoreImpl.class.getName());
@@ -1382,8 +1380,7 @@ public void shouldAddHooksVarArgsAndGetGraphHooks(@Mock final GraphHook graphHoo
 
     @Test
     public void shouldAddHookAndGetGraphHooks(@Mock final GraphHook graphHook1,
-                                              @Mock final Log4jLogger graphHook3)
-            throws Exception {
+                                              @Mock final Log4jLogger graphHook3) {
         // Given
         final StoreProperties storeProperties = new StoreProperties();
         storeProperties.setStoreClass(TestStore.class.getName());
@@ -1417,8 +1414,7 @@ public void shouldAddHookAndGetGraphHooks(@Mock final GraphHook graphHook1,
 
     @Test
     public void shouldAddNamedViewResolverHookAfterNamedOperationResolver(@Mock final GraphHook graphHook1,
-                                                                          @Mock final Log4jLogger graphHook2)
-            throws Exception {
+                                                                          @Mock final Log4jLogger graphHook2) {
         // Given
         final StoreProperties storeProperties = new StoreProperties();
         storeProperties.setStoreClass(TestStore.class.getName());
@@ -1511,7 +1507,7 @@ public void shouldAddHookFromPathAndGetGraphHooks() throws Exception {
     }
 
     @Test
-    public void shouldBuildGraphFromConfigFile() throws Exception {
+    void shouldBuildGraphFromConfigFile() {
         // Given
         final StoreProperties storeProperties = new StoreProperties();
         storeProperties.setStoreClass(TestStoreImpl.class.getName());
@@ -1541,8 +1537,7 @@ public void shouldBuildGraphFromConfigFile() throws Exception {
 
     @Test
     public void shouldBuildGraphFromConfigAndMergeConfigWithExistingConfig(@Mock final GraphLibrary library1, @Mock final GraphLibrary library2,
-                                                                           @Mock final GraphHook hook1, @Mock final GraphHook hook2, @Mock final GraphHook hook3)
-            throws Exception {
+                                                                           @Mock final GraphHook hook1, @Mock final GraphHook hook2, @Mock final GraphHook hook3) {
         // Given
         final StoreProperties storeProperties = new StoreProperties();
         storeProperties.setStoreClass(TestStoreImpl.class.getName());
@@ -1591,8 +1586,7 @@ public void shouldBuildGraphFromConfigAndMergeConfigWithExistingConfig(@Mock fin
 
     @Test
     public void shouldBuildGraphFromConfigAndOverrideFields(@Mock final GraphLibrary library1, @Mock final GraphLibrary library2,
-                                                            @Mock final GraphHook hook1, @Mock final GraphHook hook2, @Mock final GraphHook hook3)
-            throws Exception {
+                                                            @Mock final GraphHook hook1, @Mock final GraphHook hook2, @Mock final GraphHook hook3) {
         // Given
         final StoreProperties storeProperties = new StoreProperties();
         storeProperties.setStoreClass(TestStoreImpl.class.getName());
@@ -1642,7 +1636,7 @@ public void shouldBuildGraphFromConfigAndOverrideFields(@Mock final GraphLibrary
     }
 
     @Test
-    public void shouldReturnClonedViewFromConfig() throws Exception {
+    void shouldReturnClonedViewFromConfig() {
         // Given
         final StoreProperties storeProperties = new StoreProperties();
         storeProperties.setStoreClass(TestStoreImpl.class.getName());
@@ -1840,8 +1834,7 @@ public void shouldCorrectlySetViewForNestedOperationChain() throws OperationExce
     }
 
     @Test
-    public void shouldThrowExceptionOnExecuteWithANullContext(@Mock final OperationChain opChain)
-            throws OperationException {
+    void shouldThrowExceptionOnExecuteWithANullContext(@Mock final OperationChain opChain) {
         // Given
         final Context context = null;
 
@@ -1860,8 +1853,7 @@ public void shouldThrowExceptionOnExecuteWithANullContext(@Mock final OperationC
     }
 
     @Test
-    public void shouldThrowExceptionOnExecuteJobWithANullContext(@Mock final OperationChain opChain)
-            throws OperationException {
+    void shouldThrowExceptionOnExecuteJobWithANullContext(@Mock final OperationChain opChain) {
         // Given
         final Context context = null;
 
@@ -1880,8 +1872,7 @@ public void shouldThrowExceptionOnExecuteJobWithANullContext(@Mock final Operati
     }
 
     @Test
-    public void shouldThrowExceptionOnExecuteWithANullUser(@Mock final OperationChain opChain)
-            throws OperationException {
+    void shouldThrowExceptionOnExecuteWithANullUser(@Mock final OperationChain opChain) {
         // Given
         final User user = null;
 
@@ -1900,8 +1891,7 @@ public void shouldThrowExceptionOnExecuteWithANullUser(@Mock final OperationChai
     }
 
     @Test
-    public void shouldThrowExceptionOnExecuteJobWithANullUser(@Mock final OperationChain opChain)
-            throws OperationException {
+    void shouldThrowExceptionOnExecuteJobWithANullUser(@Mock final OperationChain opChain) {
         // Given
         final User user = null;
 
@@ -1920,8 +1910,7 @@ public void shouldThrowExceptionOnExecuteJobWithANullUser(@Mock final OperationC
     }
 
     @Test
-    public void shouldThrowExceptionOnExecuteJobUsingJobWithANullContext(@Mock final OperationChain opChain)
-            throws OperationException {
+    void shouldThrowExceptionOnExecuteJobUsingJobWithANullContext(@Mock final OperationChain opChain) {
         // Given
         final Context context = null;
 
@@ -1942,7 +1931,7 @@ public void shouldThrowExceptionOnExecuteJobUsingJobWithANullContext(@Mock final
     }
 
     @Test
-    public void shouldThrowExceptionOnExecuteJobUsingJobWithANullOperation() throws OperationException {
+    void shouldThrowExceptionOnExecuteJobUsingJobWithANullOperation() {
         // Given
         final Context context = new Context();
 
@@ -1963,7 +1952,7 @@ public void shouldThrowExceptionOnExecuteJobUsingJobWithANullOperation() throws
     }
 
     @Test
-    public void shouldThrowExceptionOnExecuteJobUsingJobWithANullJob() throws OperationException {
+    void shouldThrowExceptionOnExecuteJobUsingJobWithANullJob() {
         // Given
         final Context context = new Context();
 
@@ -1984,8 +1973,7 @@ public void shouldThrowExceptionOnExecuteJobUsingJobWithANullJob() throws Operat
     }
 
     @Test
-    public void shouldThrowExceptionOnExecuteJobUsingJobWithANullUser(@Mock final OperationChain opChain)
-            throws OperationException {
+    void shouldThrowExceptionOnExecuteJobUsingJobWithANullUser(@Mock final OperationChain opChain) {
         // Given
         final User user = null;
 
@@ -2744,7 +2732,7 @@ protected OperationHandler<? extends AddElements> getAddElementsHandler() {
         }
 
         @Override
-        protected OperationHandler<? extends DeleteElements> getDeleteElementsHandler() {
+        protected OutputOperationHandler<DeleteElements, Long> getDeleteElementsHandler() {
             return null;
         }
 
diff --git a/core/graph/src/test/java/uk/gov/gchq/gaffer/integration/store/TestStore.java b/core/graph/src/test/java/uk/gov/gchq/gaffer/integration/store/TestStore.java
index 7a3180ee22d..66c7ea242c2 100644
--- a/core/graph/src/test/java/uk/gov/gchq/gaffer/integration/store/TestStore.java
+++ b/core/graph/src/test/java/uk/gov/gchq/gaffer/integration/store/TestStore.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2024 Crown Copyright
+ * Copyright 2016-2025 Crown Copyright
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -86,7 +86,7 @@ protected OperationHandler<? extends AddElements> getAddElementsHandler() {
     }
 
     @Override
-    protected OperationHandler<? extends DeleteElements> getDeleteElementsHandler() {
+    protected OutputOperationHandler<DeleteElements, Long> getDeleteElementsHandler() {
         return null;
     }
 
diff --git a/core/operation/src/main/java/uk/gov/gchq/gaffer/operation/impl/delete/DeleteElements.java b/core/operation/src/main/java/uk/gov/gchq/gaffer/operation/impl/delete/DeleteElements.java
index cb42b220cff..6a6995493e9 100644
--- a/core/operation/src/main/java/uk/gov/gchq/gaffer/operation/impl/delete/DeleteElements.java
+++ b/core/operation/src/main/java/uk/gov/gchq/gaffer/operation/impl/delete/DeleteElements.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2024 Crown Copyright
+ * Copyright 2024-2025 Crown Copyright
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -18,6 +18,8 @@
 
 import com.fasterxml.jackson.annotation.JsonPropertyOrder;
 import com.fasterxml.jackson.annotation.JsonTypeInfo;
+import com.fasterxml.jackson.core.type.TypeReference;
+
 import org.apache.commons.lang3.builder.EqualsBuilder;
 import org.apache.commons.lang3.builder.HashCodeBuilder;
 
@@ -25,7 +27,9 @@
 import uk.gov.gchq.gaffer.data.element.Element;
 import uk.gov.gchq.gaffer.operation.Operation;
 import uk.gov.gchq.gaffer.operation.Validatable;
+import uk.gov.gchq.gaffer.operation.io.InputOutput;
 import uk.gov.gchq.gaffer.operation.io.MultiInput;
+import uk.gov.gchq.gaffer.operation.serialisation.TypeReferenceImpl;
 import uk.gov.gchq.koryphe.Since;
 import uk.gov.gchq.koryphe.Summary;
 
@@ -50,7 +54,8 @@
 @Summary("Deletes elements")
 public class DeleteElements implements
         Validatable,
-        MultiInput<Element> {
+        MultiInput<Element>,
+        InputOutput<Iterable<? extends Element>, Long> {
     private boolean validate = true;
     private boolean skipInvalidElements;
     private Iterable<? extends Element> elements;
@@ -92,6 +97,11 @@ public void setInput(final Iterable<? extends Element> elements) {
         this.elements = elements;
     }
 
+    @Override
+    public TypeReference<Long> getOutputTypeReference() {
+        return new TypeReferenceImpl.Long();
+    }
+
     @Override
     public Map<String, String> getOptions() {
         return options;
@@ -154,7 +164,7 @@ public String toString() {
 
     public static class Builder extends Operation.BaseBuilder<DeleteElements, Builder>
             implements Validatable.Builder<DeleteElements, Builder>,
-            MultiInput.Builder<DeleteElements, Element, Builder> {
+            MultiInput.Builder<DeleteElements, Element, Builder>, InputOutput.Builder<DeleteElements, Iterable<? extends Element>, Long, Builder> {
         public Builder() {
             super(new DeleteElements());
         }
diff --git a/core/store/src/main/java/uk/gov/gchq/gaffer/store/Store.java b/core/store/src/main/java/uk/gov/gchq/gaffer/store/Store.java
index 40d37b067a1..03e55df93c7 100644
--- a/core/store/src/main/java/uk/gov/gchq/gaffer/store/Store.java
+++ b/core/store/src/main/java/uk/gov/gchq/gaffer/store/Store.java
@@ -899,7 +899,7 @@ public List<OperationChainOptimiser> getOperationChainOptimisers() {
      *
      * @return the implementation of the handler for {@link uk.gov.gchq.gaffer.operation.impl.delete.DeleteElements}
      */
-    protected abstract OperationHandler<? extends DeleteElements> getDeleteElementsHandler();
+    protected abstract OutputOperationHandler<DeleteElements, Long> getDeleteElementsHandler();
 
     /**
      * Get this Store's implementation of the handler for {@link uk.gov.gchq.gaffer.operation.DeleteAllData}.
diff --git a/core/store/src/test/java/uk/gov/gchq/gaffer/store/StoreTest.java b/core/store/src/test/java/uk/gov/gchq/gaffer/store/StoreTest.java
index 27ae65325b7..6e614b7c279 100644
--- a/core/store/src/test/java/uk/gov/gchq/gaffer/store/StoreTest.java
+++ b/core/store/src/test/java/uk/gov/gchq/gaffer/store/StoreTest.java
@@ -40,7 +40,6 @@
 import uk.gov.gchq.gaffer.data.element.LazyEntity;
 import uk.gov.gchq.gaffer.data.element.id.EntityId;
 import uk.gov.gchq.gaffer.data.elementdefinition.exception.SchemaException;
-import uk.gov.gchq.gaffer.exception.SerialisationException;
 import uk.gov.gchq.gaffer.jobtracker.Job;
 import uk.gov.gchq.gaffer.jobtracker.JobDetail;
 import uk.gov.gchq.gaffer.jobtracker.JobStatus;
@@ -420,7 +419,7 @@ public void shouldCloseOperationIfExceptionThrown(@Mock final StoreProperties pr
     }
 
     @Test
-    public void shouldThrowExceptionIfOperationChainIsInvalid(@Mock final StoreProperties properties) throws OperationException, StoreException {
+    public void shouldThrowExceptionIfOperationChainIsInvalid(@Mock final StoreProperties properties) throws StoreException {
         // Given
         final Schema schema = createSchemaMock();
         final OperationChain<?> opChain = new OperationChain<>();
@@ -440,7 +439,7 @@ public void shouldThrowExceptionIfOperationChainIsInvalid(@Mock final StorePrope
     }
 
     @Test
-    public void shouldCallDoUnhandledOperationWhenDoOperationWithUnknownOperationClass(@Mock final StoreProperties properties) throws Exception {
+    void shouldCallDoUnhandledOperationWhenDoOperationWithUnknownOperationClass(@Mock final StoreProperties properties) throws Exception {
         // Given
         final Schema schema = createSchemaMock();
         final Operation operation = new SetVariable.Builder().variableName("aVariable").input("inputString").build();
@@ -806,7 +805,7 @@ public void shouldExecuteOperationChainJob(@Mock final StoreProperties propertie
 
     @Test
     public void shouldExecuteOperationJobAndWrapJobOperationInChain(@Mock final StoreProperties properties)
-            throws OperationException, InterruptedException, StoreException, SerialisationException {
+            throws OperationException, InterruptedException, StoreException {
         // Given
         final Operation operation = new GetVariables.Builder().variableNames(Lists.newArrayList()).build();
         given(properties.getJobExecutorThreadCount()).willReturn(1);
@@ -1185,7 +1184,7 @@ protected OperationHandler<AddElements> getAddElementsHandler() {
 
 
         @Override
-        protected OperationHandler<? extends DeleteElements> getDeleteElementsHandler() {
+        protected OutputOperationHandler<DeleteElements, Long> getDeleteElementsHandler() {
             return null;
         }
 
@@ -1286,7 +1285,7 @@ protected OperationHandler<AddElements> getAddElementsHandler() {
 
 
         @Override
-        protected OperationHandler<? extends DeleteElements> getDeleteElementsHandler() {
+        protected OutputOperationHandler<DeleteElements, Long> getDeleteElementsHandler() {
             return null;
         }
 
@@ -1396,7 +1395,7 @@ protected OperationHandler<AddElements> getAddElementsHandler() {
         }
 
         @Override
-        protected OperationHandler<? extends DeleteElements> getDeleteElementsHandler() {
+        protected OutputOperationHandler<DeleteElements, Long> getDeleteElementsHandler() {
             return null;
         }
 
diff --git a/core/store/src/test/java/uk/gov/gchq/gaffer/store/integration/StoreIT.java b/core/store/src/test/java/uk/gov/gchq/gaffer/store/integration/StoreIT.java
index 64f4d663311..a6806cdfa09 100644
--- a/core/store/src/test/java/uk/gov/gchq/gaffer/store/integration/StoreIT.java
+++ b/core/store/src/test/java/uk/gov/gchq/gaffer/store/integration/StoreIT.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2024 Crown Copyright
+ * Copyright 2016-2025 Crown Copyright
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -145,7 +145,7 @@ protected OperationHandler<? extends AddElements> getAddElementsHandler() {
         }
 
         @Override
-        protected OperationHandler<? extends DeleteElements> getDeleteElementsHandler() {
+        protected OutputOperationHandler<DeleteElements, Long> getDeleteElementsHandler() {
             return null;
         }
 
diff --git a/core/store/src/test/java/uk/gov/gchq/gaffer/store/operation/handler/TestAddToGraphLibraryImpl.java b/core/store/src/test/java/uk/gov/gchq/gaffer/store/operation/handler/TestAddToGraphLibraryImpl.java
index 1ce44a44781..8e5f943ad2f 100644
--- a/core/store/src/test/java/uk/gov/gchq/gaffer/store/operation/handler/TestAddToGraphLibraryImpl.java
+++ b/core/store/src/test/java/uk/gov/gchq/gaffer/store/operation/handler/TestAddToGraphLibraryImpl.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2017-2024 Crown Copyright
+ * Copyright 2017-2025 Crown Copyright
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -74,7 +74,7 @@ protected Class<? extends Serialiser> getRequiredParentSerialiserClass() {
     }
 
     @Override
-    protected OperationHandler<? extends DeleteElements> getDeleteElementsHandler() {
+    protected OutputOperationHandler<DeleteElements, Long> getDeleteElementsHandler() {
         return null;
     }
 }
diff --git a/store-implementation/accumulo-store/src/main/java/uk/gov/gchq/gaffer/accumulostore/AccumuloStore.java b/store-implementation/accumulo-store/src/main/java/uk/gov/gchq/gaffer/accumulostore/AccumuloStore.java
index 8e2ea59d92f..67131661c8d 100644
--- a/store-implementation/accumulo-store/src/main/java/uk/gov/gchq/gaffer/accumulostore/AccumuloStore.java
+++ b/store-implementation/accumulo-store/src/main/java/uk/gov/gchq/gaffer/accumulostore/AccumuloStore.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2024 Crown Copyright
+ * Copyright 2016-2025 Crown Copyright
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -443,7 +443,7 @@ protected OutputOperationHandler<GetTraits, Set<StoreTrait>> getGetTraitsHandler
     }
 
     @Override
-    protected OperationHandler<? extends DeleteElements> getDeleteElementsHandler() {
+    protected OutputOperationHandler<DeleteElements, Long> getDeleteElementsHandler() {
         return new DeleteElementsHandler();
     }
 
diff --git a/store-implementation/accumulo-store/src/main/java/uk/gov/gchq/gaffer/accumulostore/operation/handler/DeleteElementsHandler.java b/store-implementation/accumulo-store/src/main/java/uk/gov/gchq/gaffer/accumulostore/operation/handler/DeleteElementsHandler.java
index 0ab2b3df2b9..34e39e47578 100644
--- a/store-implementation/accumulo-store/src/main/java/uk/gov/gchq/gaffer/accumulostore/operation/handler/DeleteElementsHandler.java
+++ b/store-implementation/accumulo-store/src/main/java/uk/gov/gchq/gaffer/accumulostore/operation/handler/DeleteElementsHandler.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2024 Crown Copyright
+ * Copyright 2024-2025 Crown Copyright
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,6 +16,9 @@
 
 package uk.gov.gchq.gaffer.accumulostore.operation.handler;
 
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
 import uk.gov.gchq.gaffer.accumulostore.AccumuloStore;
 import uk.gov.gchq.gaffer.data.element.Element;
 import uk.gov.gchq.gaffer.operation.OperationException;
@@ -24,20 +27,24 @@
 import uk.gov.gchq.gaffer.store.Store;
 import uk.gov.gchq.gaffer.store.StoreException;
 import uk.gov.gchq.gaffer.store.ValidatedElements;
-import uk.gov.gchq.gaffer.store.operation.handler.OperationHandler;
+import uk.gov.gchq.gaffer.store.operation.handler.OutputOperationHandler;
+
+import java.util.ArrayList;
+import java.util.List;
 
-public class DeleteElementsHandler implements OperationHandler<DeleteElements> {
+public class DeleteElementsHandler implements OutputOperationHandler<DeleteElements, Long> {
+    private static final Logger LOGGER = LoggerFactory.getLogger(DeleteElementsHandler.class);
 
     @Override
-    public Object doOperation(final DeleteElements operation,
+    public Long doOperation(final DeleteElements operation,
             final Context context, final Store store)
             throws OperationException {
-        deleteElements(operation, (AccumuloStore) store);
-        return null;
+        return deleteElements(operation, (AccumuloStore) store);
     }
 
-    private void deleteElements(final DeleteElements operation, final AccumuloStore store)
+    private Long deleteElements(final DeleteElements operation, final AccumuloStore store)
             throws OperationException {
+        final List<String> deletedElements = new ArrayList<>();
         try {
             final Iterable<? extends Element> validatedElements;
             if (operation.isValidate()) {
@@ -46,9 +53,17 @@ private void deleteElements(final DeleteElements operation, final AccumuloStore
             } else {
                 validatedElements = operation.getInput();
             }
+
+            for (final Element el : validatedElements) {
+                deletedElements.add(el.toString());
+            }
+            LOGGER.debug("Deleting elements: {}", deletedElements);
+
             store.deleteElements(validatedElements);
         } catch (final StoreException e) {
             throw new OperationException("Failed to delete elements", e);
         }
+
+        return (long) deletedElements.size();
     }
 }
diff --git a/store-implementation/accumulo-store/src/test/java/uk/gov/gchq/gaffer/accumulostore/integration/delete/AbstractDeletedElementsIT.java b/store-implementation/accumulo-store/src/test/java/uk/gov/gchq/gaffer/accumulostore/integration/delete/AbstractDeletedElementsIT.java
index 2835ed6ae3d..14688945e1f 100644
--- a/store-implementation/accumulo-store/src/test/java/uk/gov/gchq/gaffer/accumulostore/integration/delete/AbstractDeletedElementsIT.java
+++ b/store-implementation/accumulo-store/src/test/java/uk/gov/gchq/gaffer/accumulostore/integration/delete/AbstractDeletedElementsIT.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2018-2024 Crown Copyright
+ * Copyright 2018-2025 Crown Copyright
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -114,7 +114,7 @@ public void shouldNotReturnDeletedElements() throws Exception {
         assertElements((Iterable) elements, resultBefore);
 
         // When
-        final OperationChain<Void> chain = new OperationChain.Builder()
+        final OperationChain<Long> chain = new OperationChain.Builder()
                 .first(new GetElements.Builder()
                         .input(new EntitySeed("1"))
                         .build())
diff --git a/store-implementation/accumulo-store/src/test/java/uk/gov/gchq/gaffer/accumulostore/operation/handler/DeleteElementsHandlerTest.java b/store-implementation/accumulo-store/src/test/java/uk/gov/gchq/gaffer/accumulostore/operation/handler/DeleteElementsHandlerTest.java
index 1b7e0e05894..3447b8c66ac 100644
--- a/store-implementation/accumulo-store/src/test/java/uk/gov/gchq/gaffer/accumulostore/operation/handler/DeleteElementsHandlerTest.java
+++ b/store-implementation/accumulo-store/src/test/java/uk/gov/gchq/gaffer/accumulostore/operation/handler/DeleteElementsHandlerTest.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2024 Crown Copyright
+ * Copyright 2024-2025 Crown Copyright
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -27,6 +27,7 @@
 import uk.gov.gchq.gaffer.store.StoreException;
 import uk.gov.gchq.gaffer.store.ValidatedElements;
 
+import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.ArgumentMatchers.anyIterable;
@@ -45,7 +46,8 @@ void shouldDoOperationValidated() throws Exception {
                 .build();
 
         AccumuloStore store = Mockito.mock(AccumuloStore.class);
-        handler.doOperation(op, new Context(), store);
+        final Object elementCount = handler.doOperation(op, new Context(), store);
+        assertThat(elementCount).isEqualTo(1L);
 
         verify(store).deleteElements(any(ValidatedElements.class));
     }
@@ -60,7 +62,8 @@ void shouldDoOperationNotValidated() throws Exception {
                 .build();
 
         AccumuloStore store = Mockito.mock(AccumuloStore.class);
-        handler.doOperation(op, new Context(), store);
+        final Object elementCount = handler.doOperation(op, new Context(), store);
+        assertThat(elementCount).isEqualTo(1L);
 
         verify(store).deleteElements(anyIterable());
     }
diff --git a/store-implementation/federated-store/src/main/java/uk/gov/gchq/gaffer/federatedstore/FederatedStore.java b/store-implementation/federated-store/src/main/java/uk/gov/gchq/gaffer/federatedstore/FederatedStore.java
index 6b8d4780c8b..5f58b9aff63 100644
--- a/store-implementation/federated-store/src/main/java/uk/gov/gchq/gaffer/federatedstore/FederatedStore.java
+++ b/store-implementation/federated-store/src/main/java/uk/gov/gchq/gaffer/federatedstore/FederatedStore.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2017-2024 Crown Copyright
+ * Copyright 2017-2025 Crown Copyright
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -550,8 +550,8 @@ protected OutputOperationHandler<GetAllElements, Iterable<? extends Element>> ge
     }
 
     @Override
-    protected OperationHandler<? extends DeleteElements> getDeleteElementsHandler() {
-        return new FederatedNoOutputHandler<>();
+    protected OutputOperationHandler<DeleteElements, Long> getDeleteElementsHandler() {
+        return new FederatedOutputHandler<>();
     }
 
     @Override
diff --git a/store-implementation/federated-store/src/test/java/uk/gov/gchq/gaffer/federatedstore/operation/handler/impl/FederatedDeleteElementsTest.java b/store-implementation/federated-store/src/test/java/uk/gov/gchq/gaffer/federatedstore/operation/handler/impl/FederatedDeleteElementsTest.java
index badad7f056b..38c8c5db433 100644
--- a/store-implementation/federated-store/src/test/java/uk/gov/gchq/gaffer/federatedstore/operation/handler/impl/FederatedDeleteElementsTest.java
+++ b/store-implementation/federated-store/src/test/java/uk/gov/gchq/gaffer/federatedstore/operation/handler/impl/FederatedDeleteElementsTest.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2024 Crown Copyright
+ * Copyright 2024-2025 Crown Copyright
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -86,7 +86,7 @@ public void setUp() throws Exception {
     @Test
     void shouldDeleteEntityFromSingleGraphWithMapStore() throws Exception {
         // When
-        final OperationChain<Void> chain = new OperationChain.Builder()
+        final OperationChain<Long> chain = new OperationChain.Builder()
                 .first(new GetElements.Builder()
                         .input(new EntitySeed("1"))
                         .view(new View.Builder().entity(GROUP_BASIC_ENTITY).build())
@@ -108,7 +108,7 @@ void shouldDeleteEntityFromSingleGraphWithMapStore() throws Exception {
     @Test
     void shouldDeleteEdgeFromSingleGraphWithMapStore() throws Exception {
         // When
-        final OperationChain<Void> chain = new OperationChain.Builder()
+        final OperationChain<Long> chain = new OperationChain.Builder()
                 .first(new GetElements.Builder()
                         .input(new EdgeSeed("1", "2"))
                         .view(new View.Builder().edge(GROUP_BASIC_EDGE).build())
@@ -130,7 +130,7 @@ void shouldDeleteEdgeFromSingleGraphWithMapStore() throws Exception {
     @Test
     void shouldDeleteEntityAndEdgesFromSingleGraphhWithMapStore() throws Exception {
         // Given/When
-        final OperationChain<Void> chain = new OperationChain.Builder()
+        final OperationChain<Long> chain = new OperationChain.Builder()
                 .first(new GetElements.Builder()
                         .input(new EntitySeed("2"))
                         .build())
@@ -152,7 +152,7 @@ void shouldDeleteEntityAndEdgesFromSingleGraphhWithMapStore() throws Exception {
     @Test
     void shouldDeleteEntityFromBothGraphsWithMapStore() throws Exception {
         // When
-        final OperationChain<Void> chain = new OperationChain.Builder()
+        final OperationChain<Long> chain = new OperationChain.Builder()
                 .first(new GetElements.Builder()
                         .input(new EntitySeed("1"))
                         .view(new View.Builder().entity(GROUP_BASIC_ENTITY).build())
@@ -174,7 +174,7 @@ void shouldDeleteEntityFromBothGraphsWithMapStore() throws Exception {
     @Test
     void shouldDeleteEdgeFromBothGraphsWithMapStore() throws Exception {
         // When
-        final OperationChain<Void> chain = new OperationChain.Builder()
+        final OperationChain<Long> chain = new OperationChain.Builder()
                 .first(new GetElements.Builder()
                         .input(new EdgeSeed("1", "2"))
                         .view(new View.Builder().edge(GROUP_BASIC_EDGE).build())
@@ -196,7 +196,7 @@ void shouldDeleteEdgeFromBothGraphsWithMapStore() throws Exception {
     @Test
     void shouldDeleteEntityAndEdgesFromBothGraphshWithMapStore() throws Exception {
         // Given/When
-        final OperationChain<Void> chain = new OperationChain.Builder()
+        final OperationChain<Long> chain = new OperationChain.Builder()
                 .first(new GetElements.Builder()
                         .input(new EntitySeed("3"))
                         .build())
@@ -217,7 +217,7 @@ void shouldDeleteEntityAndEdgesFromBothGraphshWithMapStore() throws Exception {
     @Test
     void shouldDeleteEntityFromSingleGraphWithAccumuloStore() throws Exception {
         // When
-        final OperationChain<Void> chain = new OperationChain.Builder()
+        final OperationChain<Long> chain = new OperationChain.Builder()
                 .first(new GetElements.Builder()
                         .input(new EntitySeed("1"))
                         .view(new View.Builder().entity(GROUP_BASIC_ENTITY).build())
@@ -239,7 +239,7 @@ void shouldDeleteEntityFromSingleGraphWithAccumuloStore() throws Exception {
     @Test
     void shouldDeleteEdgeFromSingleGraphWithAccumuloStore() throws Exception {
         // When
-        final OperationChain<Void> chain = new OperationChain.Builder()
+        final OperationChain<Long> chain = new OperationChain.Builder()
                 .first(new GetElements.Builder()
                         .input(new EdgeSeed("1", "2"))
                         .view(new View.Builder().edge(GROUP_BASIC_EDGE).build())
@@ -261,7 +261,7 @@ void shouldDeleteEdgeFromSingleGraphWithAccumuloStore() throws Exception {
     @Test
     void shouldDeleteEntityAndEdgesFromSingleGraphhWithAccumuloStore() throws Exception {
         // Given/When
-        final OperationChain<Void> chain = new OperationChain.Builder()
+        final OperationChain<Long> chain = new OperationChain.Builder()
                 .first(new GetElements.Builder()
                         .input(new EntitySeed("2"))
                         .build())
@@ -283,7 +283,7 @@ void shouldDeleteEntityAndEdgesFromSingleGraphhWithAccumuloStore() throws Except
     @Test
     void shouldDeleteEntityFromBothGraphsWithAccumuloStore() throws Exception {
         // When
-        final OperationChain<Void> chain = new OperationChain.Builder()
+        final OperationChain<Long> chain = new OperationChain.Builder()
                 .first(new GetElements.Builder()
                         .input(new EntitySeed("1"))
                         .view(new View.Builder().entity(GROUP_BASIC_ENTITY).build())
@@ -305,7 +305,7 @@ void shouldDeleteEntityFromBothGraphsWithAccumuloStore() throws Exception {
     @Test
     void shouldDeleteEdgeFromBothGraphsWithAccumuloStore() throws Exception {
         // When
-        final OperationChain<Void> chain = new OperationChain.Builder()
+        final OperationChain<Long> chain = new OperationChain.Builder()
                 .first(new GetElements.Builder()
                         .input(new EdgeSeed("1", "2"))
                         .view(new View.Builder().edge(GROUP_BASIC_EDGE).build())
@@ -327,7 +327,7 @@ void shouldDeleteEdgeFromBothGraphsWithAccumuloStore() throws Exception {
     @Test
     void shouldDeleteEntityAndEdgesFromBothGraphshWithAccumuloStore() throws Exception {
         // Given/When
-        final OperationChain<Void> chain = new OperationChain.Builder()
+        final OperationChain<Long> chain = new OperationChain.Builder()
                 .first(new GetElements.Builder()
                         .input(new EntitySeed("3"))
                         .build())
diff --git a/store-implementation/federated-store/src/test/java/uk/gov/gchq/gaffer/federatedstore/operation/handler/impl/FederatedGetTraitsHandlerTest.java b/store-implementation/federated-store/src/test/java/uk/gov/gchq/gaffer/federatedstore/operation/handler/impl/FederatedGetTraitsHandlerTest.java
index b06a9b35a70..58084c3920e 100644
--- a/store-implementation/federated-store/src/test/java/uk/gov/gchq/gaffer/federatedstore/operation/handler/impl/FederatedGetTraitsHandlerTest.java
+++ b/store-implementation/federated-store/src/test/java/uk/gov/gchq/gaffer/federatedstore/operation/handler/impl/FederatedGetTraitsHandlerTest.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2018-2024 Crown Copyright
+ * Copyright 2018-2025 Crown Copyright
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -288,7 +288,7 @@ protected OperationHandler<? extends AddElements> getAddElementsHandler() {
         }
 
         @Override
-        protected OperationHandler<? extends DeleteElements> getDeleteElementsHandler() {
+        protected OutputOperationHandler<DeleteElements, Long> getDeleteElementsHandler() {
             return null;
         }
 
diff --git a/store-implementation/map-store/src/main/java/uk/gov/gchq/gaffer/mapstore/MapStore.java b/store-implementation/map-store/src/main/java/uk/gov/gchq/gaffer/mapstore/MapStore.java
index 528632ce895..9ab0624a971 100644
--- a/store-implementation/map-store/src/main/java/uk/gov/gchq/gaffer/mapstore/MapStore.java
+++ b/store-implementation/map-store/src/main/java/uk/gov/gchq/gaffer/mapstore/MapStore.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2017-2024 Crown Copyright
+ * Copyright 2017-2025 Crown Copyright
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -176,7 +176,7 @@ protected OperationHandler<? extends AddElements> getAddElementsHandler() {
     }
 
     @Override
-    protected OperationHandler<? extends DeleteElements> getDeleteElementsHandler() {
+    protected OutputOperationHandler<DeleteElements, Long> getDeleteElementsHandler() {
         return new DeleteElementsHandler();
     }
 
diff --git a/store-implementation/map-store/src/main/java/uk/gov/gchq/gaffer/mapstore/impl/DeleteElementsHandler.java b/store-implementation/map-store/src/main/java/uk/gov/gchq/gaffer/mapstore/impl/DeleteElementsHandler.java
index 99e05619494..11946a28584 100644
--- a/store-implementation/map-store/src/main/java/uk/gov/gchq/gaffer/mapstore/impl/DeleteElementsHandler.java
+++ b/store-implementation/map-store/src/main/java/uk/gov/gchq/gaffer/mapstore/impl/DeleteElementsHandler.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2024 Crown Copyright
+ * Copyright 2024-2025 Crown Copyright
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -31,31 +31,39 @@
 import uk.gov.gchq.gaffer.store.Context;
 import uk.gov.gchq.gaffer.store.Store;
 import uk.gov.gchq.gaffer.store.ValidatedElements;
-import uk.gov.gchq.gaffer.store.operation.handler.OperationHandler;
+import uk.gov.gchq.gaffer.store.operation.handler.OutputOperationHandler;
 import uk.gov.gchq.gaffer.store.schema.Schema;
 import uk.gov.gchq.gaffer.store.util.AggregatorUtil;
 
+import java.util.ArrayList;
+import java.util.List;
+
 /**
-    * An {@link OperationHandler} for the {@link DeleteElements} operation on the
-    * {@link MapStore}.
+    * An {@link OutputOperationHandler} for the {@link DeleteElements} operation on the
+    * {@link MapStore}. Returns a string of how many elements have been deleted.
 */
-public class DeleteElementsHandler implements OperationHandler<DeleteElements> {
+public class DeleteElementsHandler implements OutputOperationHandler<DeleteElements, Long> {
     private static final Logger LOGGER = LoggerFactory.getLogger(DeleteElementsHandler.class);
 
     @Override
-    public Object doOperation(final DeleteElements deleteElements, final Context context, final Store store) {
+    public Long doOperation(final DeleteElements deleteElements, final Context context, final Store store) {
         Iterable<? extends Element> elements = deleteElements.getInput();
         if (deleteElements.isValidate()) {
             elements = new ValidatedElements(elements, store.getSchema(), deleteElements.isSkipInvalidElements());
         }
 
-        deleteElements(elements, (MapStore) store);
-        return null;
+        return deleteElements(elements, (MapStore) store);
     }
 
-    private void deleteElements(final Iterable<? extends Element> elements, final MapStore mapStore) {
+    private Long deleteElements(final Iterable<? extends Element> elements, final MapStore mapStore) {
         final MapImpl mapImpl = mapStore.getMapImpl();
         final Schema schema = mapStore.getSchema();
+        final List<String> deletedElements = new ArrayList<>();
+
+        for (final Element el : elements) {
+            deletedElements.add(el.toString());
+        }
+        LOGGER.debug("Deleting elements: {}", deletedElements);
 
         final int bufferSize = mapStore.getProperties().getIngestBufferSize();
 
@@ -67,6 +75,8 @@ private void deleteElements(final Iterable<? extends Element> elements, final Ma
             // Stream of lists that gets each batch
             Streams.toBatches(elements, bufferSize).forEach(batch -> deleteBatch(mapImpl, schema, AggregatorUtil.ingestAggregate(batch, schema)));
         }
+
+        return (long) deletedElements.size();
     }
 
     private void deleteBatch(final MapImpl mapImpl, final Schema schema, final Iterable<? extends Element> elements) {
diff --git a/store-implementation/map-store/src/test/java/uk/gov/gchq/gaffer/mapstore/impl/DeleteElementsHandlerTest.java b/store-implementation/map-store/src/test/java/uk/gov/gchq/gaffer/mapstore/impl/DeleteElementsHandlerTest.java
index a1cca81557b..dcf80460534 100644
--- a/store-implementation/map-store/src/test/java/uk/gov/gchq/gaffer/mapstore/impl/DeleteElementsHandlerTest.java
+++ b/store-implementation/map-store/src/test/java/uk/gov/gchq/gaffer/mapstore/impl/DeleteElementsHandlerTest.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2024 Crown Copyright
+ * Copyright 2024-2025 Crown Copyright
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -76,7 +76,7 @@ void shouldDeleteEntityOnlyForAggregatedGraph() throws OperationException {
         // Given/When
 
         // Delete Vertex A
-        final OperationChain<Void> chain = new OperationChain.Builder()
+        final OperationChain<Long> chain = new OperationChain.Builder()
                 .first(new GetElements.Builder()
                         .input(new EntitySeed("A"))
                         .view(ENTITY_VIEW)
@@ -84,7 +84,8 @@ void shouldDeleteEntityOnlyForAggregatedGraph() throws OperationException {
                 .then(new DeleteElements())
                 .build();
 
-        aggregatedGraph.execute(chain, USER);
+        final Object deletedCount = aggregatedGraph.execute(chain, USER);
+        assertThat(deletedCount).isEqualTo(1L);
 
         // Then
 
@@ -111,7 +112,7 @@ void shouldDeleteEdgeOnlyForAggregatedGraph() throws OperationException {
         // Given/When
 
         // Delete Edge B->C
-        final OperationChain<Void> chain = new OperationChain.Builder()
+        final OperationChain<Long> chain = new OperationChain.Builder()
                 .first(new GetElements.Builder()
                         .input(new EdgeSeed("B", "C"))
                         .view(EDGE_VIEW)
@@ -119,7 +120,8 @@ void shouldDeleteEdgeOnlyForAggregatedGraph() throws OperationException {
                 .then(new DeleteElements())
                 .build();
 
-        aggregatedGraph.execute(chain, USER);
+        final Object elementCount = aggregatedGraph.execute(chain, USER);
+        assertThat(elementCount).isEqualTo(1L);
 
         // Then
 
@@ -146,7 +148,7 @@ void shouldDeleteEntityOnlyForNonAggregatedGraph() throws OperationException {
         // Given/When
 
         // Delete Vertex A
-        final OperationChain<Void> chain = new OperationChain.Builder()
+        final OperationChain<Long> chain = new OperationChain.Builder()
                 .first(new GetElements.Builder()
                         .input(new EntitySeed("A"))
                         .view(ENTITY_VIEW)
@@ -154,7 +156,8 @@ void shouldDeleteEntityOnlyForNonAggregatedGraph() throws OperationException {
                 .then(new DeleteElements())
                 .build();
 
-        nonAggregatedGraph.execute(chain, USER);
+        final Object elementCount = nonAggregatedGraph.execute(chain, USER);
+        assertThat(elementCount).isEqualTo(1L);
 
         // Then
 
@@ -182,7 +185,7 @@ void shouldDeleteEdgeOnlyForNonAggregatedGraph() throws OperationException {
         // When
 
         // Delete Edge B->C
-        final OperationChain<Void> chain = new OperationChain.Builder()
+        final OperationChain<Long> chain = new OperationChain.Builder()
                 .first(new GetElements.Builder()
                         .input(new EdgeSeed("B", "C"))
                         .view(EDGE_VIEW)
@@ -190,7 +193,8 @@ void shouldDeleteEdgeOnlyForNonAggregatedGraph() throws OperationException {
                 .then(new DeleteElements())
                 .build();
 
-        nonAggregatedGraph.execute(chain, USER);
+        final Object elementCount = nonAggregatedGraph.execute(chain, USER);
+        assertThat(elementCount).isEqualTo(1L);
 
         // Then
 
@@ -217,14 +221,15 @@ void shouldDeleteEntityAndEdgeForAggregatedGraph() throws OperationException {
         // Given/When
 
         // Delete Vertex A and its edges
-        final OperationChain<Void> chain = new OperationChain.Builder()
+        final OperationChain<Long> chain = new OperationChain.Builder()
                 .first(new GetElements.Builder()
                         .input(new EntitySeed("A"))
                         .build())
                 .then(new DeleteElements())
                 .build();
 
-        aggregatedGraph.execute(chain, USER);
+        final Object elementCount = aggregatedGraph.execute(chain, USER);
+        assertThat(elementCount).isEqualTo(2L);
 
         // Then
 
@@ -249,14 +254,15 @@ void shouldDeleteEntityAndEdgeForNonAggregatedGraph() throws OperationException
         // Given/When
 
         // Delete Vertex A and its edges
-        final OperationChain<Void> chain = new OperationChain.Builder()
+        final OperationChain<Long> chain = new OperationChain.Builder()
                 .first(new GetElements.Builder()
                         .input(new EntitySeed("A"))
                         .build())
                 .then(new DeleteElements())
                 .build();
 
-        nonAggregatedGraph.execute(chain, USER);
+        final Object elementCount = nonAggregatedGraph.execute(chain, USER);
+        assertThat(elementCount).isEqualTo(2L);
 
         // Then
 
@@ -281,14 +287,15 @@ void shouldDeleteEntityAndAllEdgesForAggregatedGraph() throws OperationException
         // Given/When
 
         // Delete Vertex B and its edges
-        final OperationChain<Void> chain = new OperationChain.Builder()
+        final OperationChain<Long> chain = new OperationChain.Builder()
                 .first(new GetElements.Builder()
                         .input(new EntitySeed("B"))
                         .build())
                 .then(new DeleteElements())
                 .build();
 
-        aggregatedGraph.execute(chain, USER);
+        final Object elementCount = aggregatedGraph.execute(chain, USER);
+        assertThat(elementCount).isEqualTo(3L);
 
         // Then
 
@@ -313,14 +320,15 @@ void shouldDeleteEntityAndAllEdgesForNonAggregatedGraph() throws OperationExcept
         // Given/When
 
         // Delete Vertex B and its edges
-        final OperationChain<Void> chain = new OperationChain.Builder()
+        final OperationChain<Long> chain = new OperationChain.Builder()
                 .first(new GetElements.Builder()
                         .input(new EntitySeed("B"))
                         .build())
                 .then(new DeleteElements())
                 .build();
 
-        nonAggregatedGraph.execute(chain, USER);
+        final Object elementCount = nonAggregatedGraph.execute(chain, USER);
+        assertThat(elementCount).isEqualTo(3L);
 
         // Then
 
@@ -345,13 +353,14 @@ void shouldDeleteAll() throws OperationException {
         // Given/When
 
         // Delete all
-        final OperationChain<Void> chain = new OperationChain.Builder()
+        final OperationChain<Long> chain = new OperationChain.Builder()
                 .first(new GetAllElements.Builder()
                         .build())
                 .then(new DeleteElements())
                 .build();
 
-        aggregatedGraph.execute(chain, USER);
+        final Object elementCount = aggregatedGraph.execute(chain, USER);
+        assertThat(elementCount).isEqualTo(5L);
 
         // Then
 
@@ -384,7 +393,7 @@ void shouldDeleteElementsInBatches() throws StoreException, OperationException {
         // When
 
         // Delete all
-        final OperationChain<Void> chain = new OperationChain.Builder()
+        final OperationChain<Long> chain = new OperationChain.Builder()
                 .first(new GetAllElements.Builder()
                         .build())
                 .then(new DeleteElements())
diff --git a/store-implementation/proxy-store/src/main/java/uk/gov/gchq/gaffer/proxystore/ProxyStore.java b/store-implementation/proxy-store/src/main/java/uk/gov/gchq/gaffer/proxystore/ProxyStore.java
index dd49f4cb214..8dfaf951429 100644
--- a/store-implementation/proxy-store/src/main/java/uk/gov/gchq/gaffer/proxystore/ProxyStore.java
+++ b/store-implementation/proxy-store/src/main/java/uk/gov/gchq/gaffer/proxystore/ProxyStore.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2024 Crown Copyright
+ * Copyright 2016-2025 Crown Copyright
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -366,7 +366,7 @@ protected OperationHandler<? extends AddElements> getAddElementsHandler() {
     }
 
     @Override
-    protected OperationHandler<? extends DeleteElements> getDeleteElementsHandler() {
+    protected OutputOperationHandler<DeleteElements, Long> getDeleteElementsHandler() {
         return null;
     }
 
diff --git a/store-implementation/simple-federated-store/src/main/java/uk/gov/gchq/gaffer/federated/simple/FederatedStore.java b/store-implementation/simple-federated-store/src/main/java/uk/gov/gchq/gaffer/federated/simple/FederatedStore.java
index 8bd4372c0aa..80c01f077cb 100644
--- a/store-implementation/simple-federated-store/src/main/java/uk/gov/gchq/gaffer/federated/simple/FederatedStore.java
+++ b/store-implementation/simple-federated-store/src/main/java/uk/gov/gchq/gaffer/federated/simple/FederatedStore.java
@@ -441,8 +441,8 @@ protected OperationHandler<? extends AddElements> getAddElementsHandler() {
     }
 
     @Override
-    protected OperationHandler<? extends DeleteElements> getDeleteElementsHandler() {
-        return new FederatedOperationHandler<>();
+    protected OutputOperationHandler<DeleteElements, Long> getDeleteElementsHandler() {
+        return new FederatedOutputHandler<>();
     }
 
     @Override