A scrapped car number plate

Every number plate represents a specific vehicle. If that vehicle is destroyed, then the number plate will be destroyed, too. Unfortunately, keeping your number plate is not as simple as taking it off of your vehicle and then sticking it onto another.

If you choose to not tell the DVLA that you'd like to retain your number plate, it will simply disappear along with your vehicle, and there is no way to bring it back into circulation.