jlg6184: Not sure if you would know, but is this site strictly for UK users, or is it for anyone? Also the Steam games they sell, are they actually licensed to sell them? I have heard Steam can get quite irritated at 3rd party vendors selling their keys, and have been known to remove games bought through said vendors.Also (first question may answer this) but are the Steam keys region free, or only UK based?
1) Greenman Gaming can be used worldwide, however, they are now introducing regional restrictions. Affected games will display a message indicating such.
2) They get their keys from the publishers. So if the publisher provides them Steam based keys, then yes, they are kosher. (By the way, it is these games that are now showing regional restrictions)
3) The keys are "retail" Steam keys, meaning they are the same as the ones used for retail Steamworks games. The keys themselves are not regionally restricted, but Valve can (and have) imposed IP blocking for some regions that prevent activation of retail keys. The use of a US based VPN can get around this block.
I used a US based proxy to spend my Greenman Gaming credit on a Steam based game (basically, because I don't want to use their service anymore -- not happy with the introduction of restrictions or the 3 day activation on their DRM), but haven't tried downloading the game yet as it's showing as being 20 gigs in size so I'm not downloading that until I get my fiber optic connection in December.