Apologies for the extended downtime today. The server on which the site is hosted locked up, for no obvious reason, and didn’t reboot after power cycling. I decided to take advantage of the weekend to set up redundant discs (RAID1), but this meant copying everything across to the new disc. Things should be back to normal now.
(Worst case, the server gets backed up every night.)
Maybe I should get a Twitter account for notifications of things like this - something hosted entirely outside my systems.