I was waiting to cross a road in Central Lincoln in around 1991 when a Roller or Bentley (not sure which) trundled by with the plate 1RAF. That could not have been cheap.
Best plate I ever saw was on the front of a Lamborgini Diablo and it read T13 VOM. It took me a while to realize that if he was behind you and you looked in your rearview mirror, it read MOV E1T.