Yep, 1707 was the union of the kingdom of England with the kingdom of Scotland, 1801 brought in the kingdom of Ireland - through all this, Wales was a principality (the Prince of Wales still being a significant title), under England.
I'm curious as to what you imagine "20th Century" means exactly.
They were beautiful! (this one has extra annotations written on it by the player)
~thinks about cloth maps from Ultima games
~ heavy breathing