The black & silver plates are only legal on vehicls registered before August 1973, so that could give you a problem.
Also small plates are illegal; unless they still comply with font sizes, gaps and borders. (Possible on rear bike type plates with fewer letters/numbers)
Whether you get nicked depends on the discretion of your local plod.

Bud
__________
2003 - 4/4
£60 fine and no points for black plates.
I've been told twice by different sources that the 3w doesn't need a front plate and these were only fitted for type approval. Not required for MOT so I suppose it'll be a year or so before we find out. Seen a factory test mule and this is missing a front plate, and mine fell off, promise officer

Lastly the 3w also doesn't need front mud guards, I'm still debating if I'm going to remove mine.