When buying or selling a private / cherished number plate there is a standard transfer procedure involved. All number plate transfers have to go through the DVLA systems. There are various ways in which you can do a cherished transfer. If you wish to swap a vehicle registration number from one car to another this is possible by filling a V317 DVLA form out. To do this both vehicles have to be taxed and mot'd and the cost for this transfer is £80.
If you wish to take a number plate off a vehicle and hold it on a retention document (other wise known as a V778 DVLA form) in order to place an alternative private number plate on the vehicle, this is possible by also filling out a V317 DVLA form at a cost of £105. You are able to hold a number plate on a retention document for as long as required at a cost of £25 each year for re-newing the docuement.
If a personalised number plate has never been placed on a vehicle it is held on a certificate on entitlement (other wise known as a V750 DVLA form), and again you are able to keep a number plate on a certificate of entitlement for as long as you like at a cost of £25 per year to re-new the document.
All cherished number plate transfers can take around 4-5 weeks to complete, the time in which the transfer takes to complete varies from plate to plate.
As the popularity of private number plates has grown over the last decade many people own more than one number plate. It is also handy to be able to hold a number plate on retention or certificate if you do not have the vehicle you wish to put the number plate on. When buying a new car from a garage, most garages will now do the transfer for you if you require a private number plate putting on the car before you receive it. Most number plate dealers will deal with the agent for you so you don't even have to get involved at all.