A huge number of sites are shagged here (Woking, Surrey). It would appear to be some kind of DNS thing as it's on the initial connection to a site that fails randomly, as if it's the "lookup" for the site. Refresh a number of times and it works. The speeds are fine once it gets going so long as the content is all on that site. As soon as it needs to contact another site the page will slow down, as I assume it's making another DNS lookup.
This has been going on for a week now, and is not encouraging me to stay with the 1Meg service I just upgrade to (to "try it out")
Changing proxies doesn't help much. Occasionally it does for a short while. Even changing the upstream channel doesn't help.