Sort of true but apparently some plates are larger than they actually need to be legally..??
It is, apparently, a legal requirement to have a dealer or plate suppliers post code at the bottom of the front plate. No post code = not legal.
It sounds like yours are a dam sight more legal than mine are!
When I was getting my plates, I checked out the possibility of using foreign sized plates, as it was an Italian car, the upshot is no you can't legally, as the car is registered in the UK..!! Show plates are an option, but not actually legal either..!! If you have a private plate that does not easily look like a UK registration, then you might get away with a smaller Italian style plate, if you do get pulled you might get a fine for it though, depends on the plod..!!
It's just that most try to make it in to an advert and make it as big as they can, my plate the letters are tiny, but readable close up..!!