I always thought when taking private reg off (putting on retention) you had to immediately put old plates on and notify insurance.
Brother is changing his car and has done the retention bit but the dealer had told him he is allowed to just keep the private plates on the car until he trades it in at the weekend as there is a grace period allowed?
Have checked dvla website and there is no mention of this?
Yes, I had the same when I bought a Merc 270 CDI Estate a number of years ago. It had a private plate which I kept on until the new registrration details arrived in the post. It only took a few days, but in those few days I managed to get clocked by a camera in a bus lane. Bit embarrassing as the old owner had to send me the ticket!
After you apply
Your original number plate will usually be reassigned to your vehicle automatically, if your application is successful. This will happen straight away.
You’ll be sent:
a new log book (V5C) showing the vehicle’s replacement registration number - it can take 4 to 6 weeks to arrive
your original MOT back (if you sent it to tax the vehicle)
a V778 retention document if the private number is in your name
If the private number is in someone else’s name, the V778 document will be sent to them.
Before you can drive your vehicle, you must:
put the original or new number plates on the vehicle before you drive it
tell your insurance company your new registration number