I dont think I got fined when they pulled me (although I was fined for something else). I did have to have some legal number plates made up though, so that cost me, then had to have it stamped at an MOT garage to say it would pass with legal plates.
Swapped them back again 5minutes later
Been pulled twice again since then, both times trying to say that I was speeding, and both times the coppers mentioned my plates, saying was I lucky enough to get them with car, and we see you around cos of your plates. Neither of them mentioned them being illegal like the 1st copper. He must just have been bored. The writing is just very slightly italic