[thaumasiotes]

I've seen it stated variously that Little Britain is either Ireland, or Brittany.

For a long time I've felt that one of the traditional titles of the Russian czars, "Czar of all the Russias", was cooler than the titles I was aware of for other rulers. I was surprised to find the seal of an English queen on Wikipedia which clearly showed a Latin title translating as "Queen of all the Britains".

The switch from "King of Britain" to "King of the Britains" seems to have occurred during the reign of George III, judging by https://en.wikipedia.org/wiki/Great_Seal_of_the_Realm . None of those include an "all", but I'm sure it was present in the seal I saw.

[amenhotep]

"Britanniarum omnium"? Present from what I can tell on coins rather than the Great Seal. Also medals and maybe some other things.