There is the problem, when you DO put the plate on retention, you have 3 days to change over the plate to the old reg. The problem is they also send you a form, its only valid for 3 days to go and get the old numberplate made up at dingbro or halfords or whatever. You cannot use your old number, you must use the new number and you can only get the plate made up if you have the 3 day form dvla supplies ir you have to wait on the V5 being sent out. You will also have to inform you insurance company of the new reg number, otherwise you will be classed as uninsured and have plod stopping you every few days.