It would be helpful if ppl could give a little more detail when posting results as many so far are not at all clear. Also it seems as if ppl are under the impression that if they do not specify a proxy then they have a "regular proxy" when this is not the case.
I'm sure there used to be a sticky thread explaining how all this works but it looks as if it has become unstuck.
In brief, when you don't specify a proxy, the routers or switches load-balance web requests based on the URL over all of ntl's local proxies - the end result is that the same URL always goes to the same proxy (unless it's overloaded or down).
Therefore the concept of having a "regular proxy" when not actually specifying one is completely false.
Using one of the proxy checker web sites that displays the web headers e.g.
http://www.all-nettools.com/toolbox will only tell you which proxy is being used for
that particular URL, unless you are manually specifying a single proxy.
Also using your own local proxy server will not bypass the ntl proxies because of this upstream redirection mechanism. If you get faster results using your own local proxy server it's prolly because the object is already cached or else your proxy server is better than your PC at utilising the network connection.