Got home to find a letter from Telewest telling me we'd had a service upgrade. And so we have. It broke the internet for a while too - which was only solved by the "standard" method of turning off all the modems, routers and PCs and firing them back up.
Anyway, we appear to have video on demand from Telewest. It's a little limited at the moment, as far as I can tell it only has BBC stuff. But there does seem to be a good range of on-demand TV shows to chose from. They've also gone from having virtually no movies on demand to about 200, which is a vast improvement.
I still think the TV cable operators are going to be burried by direct downloads.