To answer the OP:
Briton
Brit
Non-Antarctican
Member of Her Majesty’s Fan Club
UKian (pronounced “Yookian”)
I was aware that some foreigners refer to “America” as including all of North and South America. In my experience, though, it’s more common to simply refer to the actual nationality (“Canadian,” “Salvadoran,” “Brazilian”) of the person being discussed.
Before the Panama Canal was dug, one might reasonably have claimed that it was all one big continent, “America.” But not since. 
It shows whatever the IOC decide. I wouldn’t want to suggest ways to influence them…but…y’know…
I don’t understand what you’re talking about, at all.
If someone takes a vehicle into a territory where a ‘NIRL’ (or any other) identification is regarded as misleading, then touch luck.
As I’ve suggested, there’s perhaps an agreement across Europe to remove the necessity of such IDs.
As for ‘nationality’, I thought that referred to people, not cars.
The GB appellation for the team is made with negotiation with the British Olympic Committee, and if it severely compromised the wishes of the Government, I’m sure that the government would have made a comment on it. Suffice to say that all seem happy to use an abbreviation that is slightly misleading
Similarly for this- if the Government wanted to regularise the situation and have a UK plate it could do so. Note my comment above that the government has not insisted that NI plates comply with EC regulations because of sensitivities in that area.
A further point is that the internet domain is .uk for the UK, but the government has also requested that .gb is also available but not used. Maybe for use when NI leaves the union.
My whole point is that not only are individuals semi-random at how they describe themselves, official definitions are additionally extremely confusing.
A nice little money spinner, selling someone in GB your NI plates. £200 Mum could have got for an HAZ plate.
Reminds me of a story regarding cars that members of the security forces had in Northern Ireland. If sold to a civilian, there was paperwork to re-register your new ex-police owned car for free. A bit unpleasant if someone had been tracking a police officer for a few weeks (although they regularly carried false plates in NI) and then shot at a car carrying a civilian. So you got free new plates courtesy of the government.
Dad, being a bit tight sometimes, decided that he’d sell the plates on his new car as he did with most new cars, earning himself a few quid. So far so good, until Mum drove the car up a checkpoint and found herself pulled over and asked, at gunpoint, if she would be so good as to tell the army why she had a police man’s car and where exactly the police man was. It took a while for Dad to let them know that said policeman had sold the car days before to Dad… Other stories like Dad stopping at the pub on the way to unlock the bank during a bomb scare or causing a bomb scare himself in Dublin can wait for another time :wally
As another aside, Dad is a member of the local car club. There’s legislation about to allow UK cars to carry ROI plates from years ago. Can’t quite remember the details (and Dad’s out so an explanation will have to wait) but it involved a little bit of permission from the relevant Irish authorities.
A Redcoat.
The Times Atlas of the World (9th Edition) listed the parts of the UK as; England and Scotland, constituent countries, Wales, principality, Northern Ireland, province.
Euro-trash!
::backs away slowly from the muttering crowd::