Will this AT&T Cyan Nokia Lumia 920 work in the UK on UK networks?

Basically I live in the UK and the only way I can get a Cyan version of the Lumia 920 is to import it. So I've found an eBay listing that I think might work for me.

http://www.ebay.com/itm/Nokia-Lumia-920-32-GB-Blue-Cyan-AT-T-Smartphone-NIB-No-CONTRACT-/230891937652?pt=Cell_Phones&hash=item35c23b5f74

I checked the specs on the listing and it says its GSM, so this means it will work in the UK with a UK sim-card right? On networks such as O2 and Vodafone?

I've contacted Nokia many times, but they keep insisting they have no idea if the Cyan version will ever be released in the UK :/