Thanks for the advice guys.
Unfortunately my worst fears have just been confirmed, it's been clocked and has over 150,000 miles on it, well thats what it had on it in early 2009. My neighbour did the check for me and made a good point that he thinks it's been used as a taxi which would explain the excessive wear on the seats - getting in and out all the time?
I'm still going to restore it as best I can as I wanted a lexus and even though I've got one with high mileage it's still a great car and as long as I make sure there's nothing wrong with it mechanically then I can crack on with the cosmetic stuff without a problem.