black number plates?

ive had black and silver plates on my mk2 and ive had two fines . 30 pound each time .
but when i brought the mk1 is had a black and silver plate on the front and the person i brought it off never had a problem and he live not far from me .
i think it is just a matter off luck ?i got told they are illegal if the car is not befor a certain year  

black and white or silver and black plates ARE illegal in this country on any car registered after 1973. if you see a new car with them it is prob registered in a british isle not sure which ones but they still allow it. mate of mine had a set but he kept getting producers for them more hassle than what its worth just get some printed yellow and white ones look just as good if you ask me.