Update, Wednesday 20 November: The system upgrade has finished and all maps are working as normal again. Thank you for your patience while we completed this work.

Original message, Monday 18 November: Some of the interactive maps on our website will not work for short periods while our mapping system is upgraded.

The update is scheduled to begin at 10am on Monday 18 November. We expect the work to finish by midday on Wednesday.

When the system is offline you will see an error message where the map would normally appear.

We apologise for any inconvenience this causes.