First off i'll advise i'm not familiar with implementing url re writing on any level.
That said I do know there are 2 types or rewrites setup for this site.
One I can locate and is solely responsible for top level rewrites (turning .com to .co.uk)
There is another rewriter implemented somehow somewhere, very early on in a pages lifecycle and I cannot find how or where the site is doing this. It's possible it's all handled in a 3rd party DLL but I would like to know the steps I might go through to prove or disprove this.
Thanks