This evening, I did some cable wiggling, and it's all OK again. Phew!
In other news, my mother today completed her course of radiotherapy. Her cancer was a class 3 - the most aggressive form - which actually appears to be rather good news, because that type aren't subtle, and with the surgeons having pulled a closely connected set of 11 nodes out, there's no sign of anything elsewhere. So it looks like it hasn't spread.
Oh, and Stena just sent me an email giving me a discount on the premium fare to get to PCon in March. So I've just gone and booked that, too. Well, it appears to have completed the transaction, to the point of giving me a booking reference number, but the site has just gone into error mode.