When I was a teacher on the of the Senior Teachers was a Geography teacher
He told us something in perfect sincerity once
You know when you drive along a road and it says
"you are leaving Wales" - obviously insert any county/country name
but then there is a significant gap before you see "Welcome to England"
well - he told us that the signs are in the right place and the gap between them is caused by the thickness of the line on the official map showing the official border location
Apparently once county/country ends at one edge of the line and the other doesn;t start until you get to the other edge of the line!!
This was from a Geography teacher - who had a proper degree in the subject and had done a proper degree level course in map making!
so it must be right
I should add that his wife - who was Head of Geography - was sitting in the same group at the time and I glanced at her while he was explaining this - and she was rolling her eyes - don;t know why - probably not connected.