I guess he lost interest then. The DVLA website says "Make sure the new keeper sends DVLA a completed V62 form to apply for a new registration certificate. Otherwise the police could still contact you if they need to make enquiries about the vehicle.
How any individual is supposed to "make sure" that someone else does what he is supposed to is a mystery to me.
It does also say "Once DVLA have updated their records you’ll get a letter within 4 weeks confirming that you’re not liable for the vehicle any more. I would be watching every post for that letter, and if it did not arrive, I would be straight on to them.
If the car was taxed, you would get the rebate fairly quickly, but since (I assume) this car is SORN'd, so no rebate. My advice would be to get it to a breaker and scrap it. They will give you a certificate of scrappage to send to VOSA, and that's the end of your liability.