Cheers for the explanation and at least I an now better informed. I will accept my ignorance to the fact that GB did not include N Ireland, which makes it strange why it was originally done.Not directly but a knock-on effect of leaving probably.
We didn't really care about Northern Ireland as much as some politicians have tried to claim they do since, hence you get silly measures like this.
New rules for driving in the EU explained and why GB number-plate stickers have been replaced
The change from the traditional GB identifiers to the new UK one is designed to be more inclusive of Northern Irelandwww.google.com