TTN
But the wiki article (yes, I know) does seem to sum it up nicely. Not our (GB&NI or UK) decision at the end of the day.
So you can hurumph into your Daily Mail a bit more (
) don't forget the international code for cars registered in the UK is also GB. Not NI, GB&NI, UK, ENG, SCOT, EUR (
), WALES or CYMRU.