Phone and report him while you know he is driving, give the reg and destination, tell them you've reported before and if they don't stop him you are going to the press, your local MP and local paper, say something along the lines of "if a child is killed and they knew...." might be a bluff but they won't take the chance. As to ownership it says on the logbook that being the registered keeper is not proof of ownership so I don't know how that would be resolved without small claims court but I've seen enough Judge Judy to know whoever turns up with the most evidence in their favour wins!....good luck hun x