diff --git a/app/dao/api_key_dao.py b/app/dao/api_key_dao.py
index 679467f4f4..f6a707bf76 100644
--- a/app/dao/api_key_dao.py
+++ b/app/dao/api_key_dao.py
@@ -68,6 +68,13 @@ def expire_api_key(service_id, api_key_id):
     db.session.add(api_key)
 
 
+@transactional
+def update_last_used_api_key(api_key_id, last_used=None) -> None:
+    api_key = ApiKey.query.filter_by(id=api_key_id).one()
+    api_key.last_used_timestamp = last_used if last_used else datetime.utcnow()
+    db.session.add(api_key)
+
+
 @transactional
 @version_class(ApiKey)
 def update_compromised_api_key_info(service_id, api_key_id, compromised_info):
diff --git a/app/dao/fact_notification_status_dao.py b/app/dao/fact_notification_status_dao.py
index bf886fbfd6..e67903428e 100644
--- a/app/dao/fact_notification_status_dao.py
+++ b/app/dao/fact_notification_status_dao.py
@@ -336,24 +336,35 @@ def get_total_notifications_sent_for_api_key(api_key_id):
 
 def get_last_send_for_api_key(api_key_id):
     """
+    SELECT last_used_timestamp as last_notification_created
+    FROM api_keys
+    WHERE id = 'api_key_id';
+
+    If last_used_timestamp is null, then check notifications table/ or notification_history.
     SELECT max(created_at) as last_notification_created
     FROM notifications
     WHERE api_key_id = 'api_key_id'
     GROUP BY api_key_id;
     """
-    notification_table = (
-        db.session.query(func.max(Notification.created_at).label("last_notification_created"))
-        .filter(Notification.api_key_id == api_key_id)
-        .all()
+    # Fetch last_used_timestamp from api_keys table
+    api_key_table = (
+        db.session.query(ApiKey.last_used_timestamp.label("last_notification_created")).filter(ApiKey.id == api_key_id).all()
     )
-    if not notification_table[0][0]:
+    if not api_key_table[0][0]:
         notification_table = (
-            db.session.query(func.max(NotificationHistory.created_at).label("last_notification_created"))
-            .filter(NotificationHistory.api_key_id == api_key_id)
+            db.session.query(func.max(Notification.created_at).label("last_notification_created"))
+            .filter(Notification.api_key_id == api_key_id)
             .all()
         )
-        notification_table = [] if notification_table[0][0] is None else notification_table
-    return notification_table
+        if not notification_table[0][0]:
+            notification_table = (
+                db.session.query(func.max(NotificationHistory.created_at).label("last_notification_created"))
+                .filter(NotificationHistory.api_key_id == api_key_id)
+                .all()
+            )
+            notification_table = [] if notification_table[0][0] is None else notification_table
+        return notification_table
+    return api_key_table
 
 
 def get_api_key_ranked_by_notifications_created(n_days_back):
diff --git a/app/notifications/process_notifications.py b/app/notifications/process_notifications.py
index 56a2dc98d3..d3dc3304c8 100644
--- a/app/notifications/process_notifications.py
+++ b/app/notifications/process_notifications.py
@@ -15,6 +15,7 @@
 from app.celery import provider_tasks
 from app.celery.letters_pdf_tasks import create_letters_pdf
 from app.config import QueueNames
+from app.dao.api_key_dao import update_last_used_api_key
 from app.dao.notifications_dao import (
     bulk_insert_notifications,
     dao_create_notification,
@@ -133,6 +134,8 @@ def persist_notification(
             if redis_store.get(redis.daily_limit_cache_key(service.id)):
                 redis_store.incr(redis.daily_limit_cache_key(service.id))
         current_app.logger.info("{} {} created at {}".format(notification_type, notification_id, notification_created_at))
+        if api_key_id:
+            update_last_used_api_key(api_key_id, notification_created_at)
     return notification
 
 
@@ -298,6 +301,7 @@ def persist_notifications(notifications: List[VerifiedNotification]) -> List[Not
     """
 
     lofnotifications = []
+    api_key_last_used = None
 
     for notification in notifications:
         notification_created_at = notification.get("created_at") or datetime.utcnow()
@@ -357,7 +361,15 @@ def persist_notifications(notifications: List[VerifiedNotification]) -> List[Not
                 notification.get("notification_created_at"),  # type: ignore
             )
         )
+        # If the bulk message is sent using an api key, we want to keep track of the last time the api key was used
+        # We will only update the api key once
+        api_key_id = notification.get("api_key_id")
+        if api_key_id:
+            api_key_last_used = datetime.utcnow()
+    if api_key_last_used:
+        update_last_used_api_key(api_key_id, api_key_last_used)
     bulk_insert_notifications(lofnotifications)
+
     return lofnotifications
 
 
diff --git a/scripts/enlarge_db/README.md b/scripts/enlarge_db/README.md
new file mode 100644
index 0000000000..b36090390b
--- /dev/null
+++ b/scripts/enlarge_db/README.md
@@ -0,0 +1,22 @@
+# Enlarge DB
+
+## Purpose
+
+The purpose of this script is add rows to the notification_history table. This is useful in estimating how long database-related infrastructure operations will take when performed on a database the same size as that in production.
+
+## How to use
+
+The script should be run in the same environment as api. Locally this can be in the api repo devcontainer, while in AWS the api kubernetes pod would be preferred.
+
+To add 2000 rows to the table with a client_reference of "test2000" run
+
+```
+cd scripts/enlarge_db
+python enlarge_db.py -n 2000 -r test2000
+```
+
+The new notifications are added in batches to improve performance, with a default batch size of 10000. You may use a different batch with the `-c` parameter, for example
+
+```
+python enlarge_db.py -n 2000 -c 101 -r test2000x101
+```
diff --git a/scripts/enlarge_db/enlarge_db.py b/scripts/enlarge_db/enlarge_db.py
new file mode 100644
index 0000000000..649e6f3032
--- /dev/null
+++ b/scripts/enlarge_db/enlarge_db.py
@@ -0,0 +1,55 @@
+
+import argparse
+import sys
+from datetime import datetime
+from typing import List
+
+from flask import Flask
+
+sys.path.append("../..")
+from app import create_app, create_uuid, db  # noqa: E402
+from app.config import Config  # noqa: E402
+from app.models import NotificationHistory  # noqa: E402
+
+DEFAULT_CHUNK_SIZE = 10000
+
+
+def create_notifications(n: int, ref: str) -> List[NotificationHistory]:
+    notifications = [
+        NotificationHistory(
+            id=create_uuid(),
+            created_at=datetime.utcnow(),
+            template_id=Config.NEW_USER_EMAIL_VERIFICATION_TEMPLATE_ID,
+            template_version=1,
+            service_id=Config.NOTIFY_SERVICE_ID,
+            notification_type="email",
+            key_type='normal',
+            client_reference=ref,
+        )
+        for _ in range(n)
+    ]
+    return notifications
+
+
+if __name__ == '__main__':
+    parser = argparse.ArgumentParser()
+    parser.add_argument("-n", "--notifications", default=1, type=int, help="number of notifications to add to the notification_history table (default 1)")
+    parser.add_argument("-r", "--reference", default="manually created", type=str, help="client reference to use for the notifications (default 'manually created')")
+    parser.add_argument("-c", "--chunksize", default=DEFAULT_CHUNK_SIZE, type=int, help=f"chunk size for bulk_save_objects (default {DEFAULT_CHUNK_SIZE})")
+    args = parser.parse_args()
+
+    app = Flask("enlarge_db")
+    create_app(app)
+
+    for notifications_done in range(0, args.notifications, args.chunksize):
+        notifications = create_notifications(min(args.chunksize, args.notifications - notifications_done), args.reference)
+        print(f"Adding {len(notifications)} notifications to notification_history")
+        with app.app_context():
+            try:
+                db.session.bulk_save_objects(notifications)
+                db.session.commit()
+            except Exception as e:
+                print(f"Error adding notifications: {e}")
+                db.session.rollback()
+                sys.exit(1)
+        print(f"Done {notifications_done+len(notifications)} / {args.notifications}")
diff --git a/tests/app/dao/test_api_key_dao.py b/tests/app/dao/test_api_key_dao.py
index 7642325ded..5e23002171 100644
--- a/tests/app/dao/test_api_key_dao.py
+++ b/tests/app/dao/test_api_key_dao.py
@@ -14,6 +14,7 @@
     resign_api_keys,
     save_model_api_key,
     update_compromised_api_key_info,
+    update_last_used_api_key,
 )
 from app.models import KEY_TYPE_NORMAL, ApiKey
 from tests.app.db import create_api_key
@@ -61,6 +62,17 @@ def test_expire_api_key_should_update_the_api_key_and_create_history_record(noti
     sorted_all_history[1].version = 2
 
 
+def test_last_used_should_update_the_api_key_and_not_create_history_record(notify_api, sample_api_key):
+    last_used = datetime.utcnow()
+    update_last_used_api_key(api_key_id=sample_api_key.id, last_used=last_used)
+    all_api_keys = get_model_api_keys(service_id=sample_api_key.service_id)
+    assert len(all_api_keys) == 1
+    assert all_api_keys[0].last_used_timestamp == last_used
+
+    all_history = sample_api_key.get_history_model().query.all()
+    assert len(all_history) == 1
+
+
 def test_update_compromised_api_key_info_and_create_history_record(notify_api, sample_api_key):
     update_compromised_api_key_info(
         service_id=sample_api_key.service_id, api_key_id=sample_api_key.id, compromised_info={"key": "value"}
diff --git a/tests/app/dao/test_fact_notification_status_dao.py b/tests/app/dao/test_fact_notification_status_dao.py
index 6e6087d2cc..663cf859f8 100644
--- a/tests/app/dao/test_fact_notification_status_dao.py
+++ b/tests/app/dao/test_fact_notification_status_dao.py
@@ -356,6 +356,14 @@ def test_get_total_notifications_sent_for_api_key(notify_db_session):
     assert dict(api_key_stats_3) == dict([(EMAIL_TYPE, total_sends), (SMS_TYPE, total_sends)])
 
 
+def test_get_last_send_for_api_key_check_last_used(notify_db_session):
+    service = create_service(service_name="First Service")
+    api_key = create_api_key(service, last_used=datetime.utcnow())
+
+    last_send = get_last_send_for_api_key(str(api_key.id))[0][0]
+    assert last_send == api_key.last_used_timestamp
+
+
 def test_get_last_send_for_api_key(notify_db_session):
     service = create_service(service_name="First Service")
     api_key = create_api_key(service)
diff --git a/tests/app/db.py b/tests/app/db.py
index 9e79f5042c..1dacec37bc 100644
--- a/tests/app/db.py
+++ b/tests/app/db.py
@@ -551,7 +551,7 @@ def create_letter_rate(
     return rate
 
 
-def create_api_key(service, key_type=KEY_TYPE_NORMAL, key_name=None):
+def create_api_key(service, key_type=KEY_TYPE_NORMAL, key_name=None, last_used=None):
     id_ = uuid.uuid4()
 
     name = key_name if key_name else "{} api key {}".format(key_type, id_)
@@ -563,6 +563,7 @@ def create_api_key(service, key_type=KEY_TYPE_NORMAL, key_name=None):
         key_type=key_type,
         id=id_,
         secret=uuid.uuid4(),
+        last_used_timestamp=last_used,
     )
     db.session.add(api_key)
     db.session.commit()
diff --git a/tests/app/notifications/test_process_notification.py b/tests/app/notifications/test_process_notification.py
index bb194d3c28..eaa0c00da0 100644
--- a/tests/app/notifications/test_process_notification.py
+++ b/tests/app/notifications/test_process_notification.py
@@ -19,6 +19,7 @@
     LETTER_TYPE,
     NORMAL,
     PRIORITY,
+    ApiKey,
     Notification,
     NotificationHistory,
     ScheduledNotification,
@@ -433,6 +434,10 @@ def test_persist_notifications_list(self, sample_job, sample_api_key, notify_db_
         assert persisted_notification[1].to == "foo2@bar.com"
         assert persisted_notification[0].service == sample_job.service
 
+        # Test that the api key last_used_timestamp got updated
+        api_key = ApiKey.query.get(sample_api_key.id)
+        assert api_key.last_used_timestamp is not None
+
     def test_persist_notifications_reply_to_text_is_original_value_if_sender_is_changed_later(
         self, sample_template, sample_api_key, mocker
     ):
@@ -913,6 +918,8 @@ def test_transform_email_notification_stores_normalised_email(
 
         assert persisted_notification.to == recipient
         assert persisted_notification.normalised_to == expected_recipient_normalised
+        api_key = ApiKey.query.get(sample_api_key.id)
+        assert api_key.last_used_timestamp is not None
 
 
 class TestDBSaveAndSendNotification: