Very interesting Will. I didn't actually know this but some very strange things have happened over the centuries. Cornwall is not regarded by the locals as being part of England but a separate country. This is apparently no longer true.
http://www.brycchancarey.com/places/cornwall/Cornwall is an odd place to have been brought up in. Most people in the United Kingdom see it as a holiday destination while the Cornish see it as a country in its own right, only incidentally connected with England. In fact, Cornwall has been part of England since the ninth century but until the sixteenth century most people spoke Cornish - properly Kernewek- a Celtic language very similar to Welsh.
Due to recent boundary changes I'm never sure where many places are any more. For example: for 100s of years the town of Bournemouth was in Hampshire. A short time ago the government decided, for what ever purpose, to redraw the boundary & make it part of Dorset instead.
During the time I worked at Gatwick Airport it was part of Crawley (West Sussex) & then Horley (Surrey). I believe it is now back in Sussex again. I assume this would affect these town's finanances considerably as the rates on the airport must bring in a vast amount in revenue. However, the airport itself has in fact not moved & it remains where it always was. ::)
These people are still at it as I believe that some places will no longer officially exist after the planned restructuring of some constituencies. These have worked fine as they are for 100s of years. I wish the politicians would make their minds up & stop messing ordinary people around to suit their devious plans.