Also Jim, make sure that when you do eventually buy the car, that you re-register it in your name asap as he will almost certainly tell them he's sold the car to you...... and if you dont tell them you've bought it, they will fine you for not telling them.

Trust me, I deal with vehicle documents and the DVLA all day long. As far as the DVLA are concerned these days, you have to look after number one and cover your back from all angles else they'll fine ya for everything!