Remember Guernsey is not in the EC, they don't have MOT's and you will have to pay import duty on it if you bring it back to mainland UK (they don't even recognise Elizabeth 2nd as the Queen, she is the Duke of Normandy to the Islanders!).

And if the owner has strictly obeyed the traffic laws over there, it will never have been out of third gear..max speed is 35 mph!

In addition don't forget this is an island 8 miles by 3 miles, surrounded by salt water and when it rains there it tends to rain salt water...