I raised a ticket with the Hosting Co. as I wasn't able to connect or contact the database server at all. Typically as soon as I'd raised the ticket the site came back up
Here's the (very prompt) response I received:
Giles wrote:Yes there was an issue not too long ago with the mysql on your server. While I am not 100% sure why the service went offline I needed to do a complete reboot of the mysql service reloading all the mysql databases.
No data was lost but there was some mysql downtime which is what caused your site to go offline.
Please let us know should you see any further issues with the server.

