A company called Kramer does exactly this kind of thing.
You can try this link to the product I think you want:
http://www.kramerelectronics.com/group1/vp6xl.html
If you have a look around their website, you will find a switcher/distributor for pretty much any signal.
Their products aren't cheap, but they are pretty much an industry standard used for commercial purposes.
If you want someone in the UK who can get their stuff, try AudioVenue (01628 633995) in Maidenhead.
I may end up with a Kramer box from there as well, although I have more sources than I can switch to a display.