Sorry to hear it rik, the law is the law end of the day
That's why there are people out there offer warranty and inspection services , for about 300 quid they go over it with a toothcomb and give you a report on the car
Put the shoe on the other foot tho , say I purchased the car from your son ragged the **** out of it on the way home and blew the engine up .... Then come knocking on the door wanting a refund ?