Thanks guys...
He won the car over a £1,000 cheaper than what they are worth. The buyer is not in the trade, he is a lawyer.
I was gutted the car went so cheap but I kept my word and delivered to him.
I'm only a part time trader from home but I have realised that buyers do try this sort of thing more and more often.
He has no intention of a refund and I have sent several replies stating it is a manufacturer's design.
See what happens now as he has replied with "don't worry for NOW I will do some further checks"