I bought some two sided adhesive tape from Ebay, its around 4mm to 5mm thick around 40mm wide
Stick two lengths of tape the full length of the number plate.
You only get one go at sticking it on, so you need a good eye for it been level, remove the backing tape and press it on. Once on it stays on.
The front plate can be bent slightly to accommodate the curve of the front bumper.