Gareth79 auteur de UK Number Plate
Hiya, I am the author of this font, I have only recently realised it has had far far more extensive use over the years than I ever imagined.
I originally created the font in 2002 because there was only one other font available (and it was £40 or something). It was traced from the prescribed font on the UK Statutory Instrument, so it's likely a derivative work of the original Crown Copyright. This was prior to the OGL that allows reuse of Crown Copyright material so I'm unsure as to it's current status, and it's something I'll try and clarify soon.
That said, versions of this typeface appear to have used EXTENSIVELY online by many large companies, and indeed the DVLA themselves on the Vehicle Information Service. (This is obvious from examining my original tracing flaws in the glyphs).
I recall I only uploaded it to some font newsgroups at the time, it has popped up on various websites like this with incorrect or missing copyright information.