Hi guys,just sold my sons car for him,it doesn't have any tax on it ,so when we finalise tomorrow and he is stopped driving it home who would be prosecuted
He does'nt need to be stopped. If you had'nt declared SORN ie off the road for whatever reason, then as the current owner your son is responsible. As a saftey measure I would annotate on a bill of sale that the purchaser is aware that the vehicle is not taxed and get him to sign it. This may help you argue a case that you were selling the car and did not want to re-tax it yourself.
when you sell the car, give a receipt for it stating price, date and the time of transaction. From that point the new owner shall be responsible for the vehicle.