To me that looks like a modern "budget" dual-suspension MTB, I highly doubt it's a genuine GT, and it's certainly not a Zaskar.
In fact it looks suspiciously similar to this frame....
http://www.all-about-the-bike.co.uk...e---fully-assembled--free-delivery-3301-p.asp
Did you also see this advert on York Gumtree, placed 22 days ago?
http://york.gumtree.com/york/90/70566790.html
If it were me I'd walk away, there's plenty of better bikes out there for £200.
My Proflex cost that amount, and although it's 13years old it's still way way better than the bike you linked to.
Keep looking, do some research and reading, you can get a far better bike for the money.
In fact it looks suspiciously similar to this frame....
http://www.all-about-the-bike.co.uk...e---fully-assembled--free-delivery-3301-p.asp
Did you also see this advert on York Gumtree, placed 22 days ago?
http://york.gumtree.com/york/90/70566790.html
If it were me I'd walk away, there's plenty of better bikes out there for £200.
My Proflex cost that amount, and although it's 13years old it's still way way better than the bike you linked to.
Keep looking, do some research and reading, you can get a far better bike for the money.