I'm guessing its cost, Cogent is well known for being a cheap provider, most 'pile em high' type internet businesses (Newshosting/Newsreader/Filefront/EV1) will have Cogent bandwidth for their High Usage situations and I'm guessing its also cheaper for NTL to route using Cogent.
None of this helps us poor customers of course

And other ISP's seem to manage with Cogent just fine.
Perhaps Telia is a cheap route as well ? might explain why it also suffers from about 12pm onwards....
In fact after more research it seems that NTL's peering is pretty poor all round, Easynews has a route selector tool that lets you choose the network that carries your bandwidth, their support forum is full of uk cable users that have very poor connections to them using virtually all of the networks, Level 3 works great for me to them, full speed, but the other providers (Qwest,LLNW,UU & ATT) are all very poor (mid 100k's) so thats another 4 providers that NTL seem to have poor speeds with.
I think its looking to be network probs and not proxies...it just shows as the proxies because different proxies can take different routes...or maybe it *is* the proxies, I don't know, we can witter on for ages here talking to ourselves but we need someone from NTL to answer my Responstek as promised !!