And transparent proxies being what they are, even when you're accessing legitimate content, you can end up with bizarre failures since cookies aren't working properly. Get quite a lot of "you don't have cookies enabled" errors from file transfer sites which don't occur through non-UK VPNs.

Shoddy transparent proxying and traffic shaping isn't anything new in the UK though. For the past couple of years I've frequently had Google go "down" for blocks of 5-10 minutes several times each week, yet through VPN it's fine. If you want a reliable connection at home in this country, it seems you need to just be permanently hooked up to a VPN located somewhere else.