What are the rules around the name Great Britain? For e.g. if Scotland becomes independent does it stop being appropriate or would we still be the British Isles?
Depends if you mean Great Britain the land mass or Great Britain the political union of Scotland, Wales and England. British Isles is purely geographic so less troublesome.
What are the rules around the name Great Britain? For e.g. if Scotland becomes independent does it stop being appropriate or would we still be the British Isles?