I couldnt change the V5 once I had sold the car, but surely should still be able to inform the DVLA of a change of address, which i did through the only means left to me i.e., up dating my driving license.
Yes I am now being prosecuted. and yes I didnt find out about the FPN till i received a notice of enforcement letter, the debt has increase to over £1,000 now. contacted HMCTS and they basically wouldnt respond to my claim that the FPN got sent to wrong address but just gave me a settlement figure with DVLA of £345