They have trashed it again in the mean time
I have restored the backup again, and this time the hourly backups will ensure we can roll back properly.
I have also blocked non-UK IP's as a temporary measure, it seems that US ones are a problem and that the spammers are using proxy servers etc...
The measure is not perfect but should keep is safe until a decision is made as to what can be done to protect the site.
Since doing it we have had 8 blocks, all from various places.
ARG.... :)
Darren