I had sold this vehicle at the time of the alleged offence – why have I received a notice?

The registered keeper details for this vehicle have been supplied by the DVLA so it appears they have not received notification of the transfer/sale from both parties; please provide details of the person or company that bought your vehicle in the S172 form provided via royal mail or online. It may also be advisable for you to contact DVLA to ensure their records are updated.