Sorry about that! As a result of it going offline, I am in talks with my hosting service as demand for bandwidth for the site from users, was spiking above the level of my allocation on my hosting package.
I am trying to determine if this is due to a problem with how databases are set, or some software glitch, or from actual demand pushing the site up against the current limits on my account.
I checked the site statistics and found that in February, which was a relatively quiet month, we still had close to 39,000 unique visitors to the site, so it may well be that I just need to get a larger hosting package. I'm not quite convinced of that though so an engineer will check out the site logs to see if there's some other reason...