I'd hate to start off on the wrong foot after lurking here for so long marky, however I really must disagree with your statement, I clearly remember the installer asking me if I had a x-over cable or dongle handy when one was first needed, I told him I didn't and he went off to his van and came back with the dongle at the top of the image (sorry for the blur, I'm too tired to configure the camera correctly) , and I'm 3/4's sure that the bottom dongle also came from an ntl install.
Maybe this is down to a lottery of installers?, maybe I'm just lucky and got an installer who is on the ball?
Cheers & respect.
Barry 'BloodyL'.
http://homepage.ntlworld.com/bloodyl/ntl_xover.jpg (Click to see image)
[Admin Edit(Mick):-Image turned to link due to size.]