diff --git a/app/broadcast_message/rest.py b/app/broadcast_message/rest.py
index 9d8dffaa5..f1e6c619d 100644
--- a/app/broadcast_message/rest.py
+++ b/app/broadcast_message/rest.py
@@ -43,10 +43,12 @@ def _parse_nullable_datetime(dt):
 
 def _update_broadcast_message(broadcast_message, new_status, updating_user):
     if updating_user not in broadcast_message.service.users:
-        raise InvalidRequest(
-            f'User {updating_user.id} cannot approve broadcast_message {broadcast_message.id} from other service',
-            status_code=400
-        )
+        #  we allow platform admins to cancel broadcasts
+        if not (new_status == BroadcastStatusType.CANCELLED and updating_user.platform_admin):
+            raise InvalidRequest(
+                f'User {updating_user.id} cannot update broadcast_message {broadcast_message.id} from other service',
+                status_code=400
+            )
 
     if new_status not in BroadcastStatusType.ALLOWED_STATUS_TRANSITIONS[broadcast_message.status]:
         raise InvalidRequest(
diff --git a/tests/app/broadcast_message/test_rest.py b/tests/app/broadcast_message/test_rest.py
index b067b8bc4..5de52f9e9 100644
--- a/tests/app/broadcast_message/test_rest.py
+++ b/tests/app/broadcast_message/test_rest.py
@@ -489,13 +489,20 @@ def test_update_broadcast_message_status_doesnt_let_you_update_other_things(admi
     }]
 
 
-def test_update_broadcast_message_status_stores_cancelled_by_and_cancelled_at(
-    admin_request, sample_broadcast_service, mocker
+@pytest.mark.parametrize('user_is_platform_admin', [True, False])
+def test_update_broadcast_message_allows_service_user_and_platform_admin_to_cancel(
+    admin_request, sample_broadcast_service, mocker, user_is_platform_admin
 ):
+    """
+    Only platform admins and users belonging to that service should be able to cancel broadcasts.
+    """
     t = create_template(sample_broadcast_service, BROADCAST_TYPE, content='emergency broadcast')
     bm = create_broadcast_message(t, status=BroadcastStatusType.BROADCASTING)
     canceller = create_user(email='canceller@gov.uk')
-    sample_broadcast_service.users.append(canceller)
+    if user_is_platform_admin:
+        canceller.platform_admin = True
+    else:
+        sample_broadcast_service.users.append(canceller)
     mock_task = mocker.patch('app.celery.broadcast_message_tasks.send_broadcast_event.apply_async')
 
     response = admin_request.post(
@@ -736,7 +743,7 @@ def test_update_broadcast_message_status_rejects_approval_from_user_not_on_that_
     )
 
     assert mock_task.called is False
-    assert 'cannot approve broadcast' in response['message']
+    assert 'cannot update broadcast' in response['message']
 
 
 @pytest.mark.parametrize('current_status, new_status', [