You can be a UK citizen but if you were not born in and don't live in the island of Britain, including its islands, you cannot be British, English, Scottish or Welsh, no matter how much you want to for ethnic/political reasons! Maybe you could qualify to play football (or cricket) for England via your grandparents (like Ireland also does in reverse) but you cannot be British, English, Scottish or Welsh- you could even vote for UKIP, God help us, but you still don't qualify.

Recent arrivals in Britain from Eastern Europe or Asia have a much better claim!
Eggshells indeed