I sold my car to a really nice guy who drove it round the block. I suggested going further to "open it up a bit" and he went a little more, but not far. He offered me a cheque, slightly below the asking price, which I agreed to but I would not release the car until cleared. I picked him up from the train station the following Saturday and he took the car. Everyone was happy! Then I received a voicemail message. The first, which horrified me, said that he'd broken down on the motorway. In subsequent messages he implied suing me, calling the police, taking legal action and said that the car was not as described. I felt verbal contact was not the best way forward so did not reply.

I wrote to him explaining just that and asked the nature of the fault. On returning from work I had a recorded letter saying "the engine failed catastrophically at speed on the M27" further stating the head gasket failed. Although, at first, I wanted to help, he said he has initiated court proceedings so I don't know what is best. He paid £800 and I know I wouldn't be happy either, but I don't know whether it was the car's fault or what he meant by "at speed". How do I stand legally?