My input on this would actually be not to blame NTL in this case. Well, other for the fact they're still using proxies.
I've had this problem before, BurstNET implimented new Denial of Server hardware, which ended up not liking the fact these ntl proxies were requesting hundreds of pages lots of times, which of course, is just what a proxy server does. In the end, burst finally resolved this by unbanning the IP's it was blocking.
The problem here lays with Limelight Networks. They provide lots of hosting to various companies. Futurenet, the magazine publication (which are sites like pcgamer, and how thewidgetshow.com's podcast) as well as media.podshow.com - which many of you may well use for various podcasts (Adam Curry's Daily Source Code, for example). Also, i believe i'm right in saying all WoW's game servers are on limelight too (but, obviously you wont notice this, cause they don't use port 80.)
Anyway, this issue first came to me last saturday, when trying to download a podcast, and i let Podshow now, finally figuring it out that it was NTL's caches (because i was able to find an NTL cache which wasn't being banned...). Podshow are supposedly looking into it, cause of course this a major problem for them, as NTL users are unable to (majoritively) download stuff from them.
I've contacted Limelight Networks and was told my ticket was accepted and would be replied too within an hour (about 16 hours ago.. mhmm. :P)
Ill keep you updated
(They also host all of MySpaces image servers, if not the main site! And, infact, NTL has the same problem back in 2005 with Limelight, according to a google:
http://www.cableforum.co.uk/board/ar...p/t-34914.html)