Depends what sort of plate it is really some are age related some aren't.
Six digit plates of the format DUB 123 were age related issue in the uk upto the early 60's.
Then you've got the plates with a letter suffix/prefix from the 60's up until the early 2000's followed by the 01/51 plates since.
As far as I'm aware special plates e.g. DUB 1 etc aren't age related at all (I'm guessing on that one though so could be wrong).