mate, I know of a few lads that are rolling in cash from selling the white stuff, they buy scoobies all the time3,4,5k and have no licence, no insurance etc etc, they just drive them then sell them on, of they get a tug the boot it and dump the car.

I would phone the dvla, explain that you have sold the car and that you sent them the log book, you may have to pay up the 40 notes, but atleast you will not get anyomore and it may be a lesson to make sure log books are sent recorded delivery.