I had a friendly warning from a Police check on stick on wing numbers on my previous Morgan 4/4
Strictly speaking they are not legal...the font on the AR Racing is reduced in size to fir the curves of the Morgan wing...I was also told by a member of AR Racing that they are considered Show Plates and fitted at owners risk.
I had no MOT issues but removed them anyway.
On my current car I have a stick on number plate on the front valence which is the correct size and font and therefore legal
I cant see many Police out with their tape measures but it is up to you..