Note: this guide refers to fitting or changing the physical plastic number plates on a vehicle. If you wish to change the registration number of the vehicle you must complete a registration transfer.
Acrylic plastic number plates are pretty tough, but they do occasionally get damaged, broken or even stolen. In such circumstances we obviously need to replace them.
Remove the old number plates from the car. If they are screwed in place then simply remove or open the plastic screw covers (if present) and undo the screws. Keep the screws in case any new screws are too small for the existing mounting holes.
If the plate is secured with double sided pads or tape you'll have to work it loose. This can take a while as the mounting pads use very strong adhesive. Pull/prise the plate away from the car keeping up a consistent force. You may find that a tool such as a wallpaper scraper can be inserted behind the plate to help loosen it.
If using screws:
Decide whether you're going to drill screw holes from the front or back of the new plate. Most plate manufacturers recommend drilling from the back, others recommend applying masking tape to the front of the plate and then drilling from the front.
Using the old plate as a template, mark the positions of the screw holes, then use a bradawl or small cross-head screwdriver to make a guide/starter mark or hole to keep the drill bit in place when drilling. (Alternatively, you may clamp the old plate in place over the new one as a jig to get the right placement for the holes.)
Place the number plate on a piece of scrap wood and then carefully drill each hole through the plate in one go. Clean any plastic swarf from the holes.
Hold the new number plate in place. If you have new screws that will fit the existing mounting holes then use them to secure the new plates in place, otherwise reuse the old screws. If you are using a Regtransfers number plate fixing kit you should use the plastic screw covers to protect the screws and help them blend in with the plate background. These covers may not fit if you are reusing old screws.
If using double-sided adhesive tape/pads:
Ensure that the back of the new number plate and the mounting surface on the car are clean and flat.
Remove the adhesive pads from their backing (but leave the backing paper on the other side that will go against the car) and stick them to the back of the number plate. The more pads you use the more secure the plate will be - but the more difficult it will be to remove if you need to change it again.
Remove the backing paper from the exposed side of the adhesive pads and carefully offer the plate up to get it in the right position. Be careful not to touch the sticky pads against the car until you are sure the plate is in the right place.
Press the number plate into position and apply firm pressure for at least 10 seconds. Ensure that you have applied pressure over all the points where adhesive pads are used. Check to ensure that the number plate is securely affixed to the car.