Not in any way seeking to induce any measure of possible anguish.
I seem to remember reading quite some years back, that if found guilty of using illegal B&W plates, it can lead to loss of right to the reg number which they display...? Further to that it seems that some time in the more recent past it is a requirement for number plates to display the post code of the company who supplied the plates..I know of one person who was stopped by traffic and had the post code issue pointed out..!