It is nice, almost certainly a 2001, however I'm not convinced it came with a Manitou shock and the one that's fitted appears to be the wrong length, but it could be a trick of the camera. I think the original has been pinched to sell at some point and they have chucked any old shock in there to make a complete frame.
Def not worth £500 though. You can buy some pretty special full sus frames in great condition for that sort of money and that's coming from an I-drive fan.