Imagine if all the great Scottish scientists were referred to as 'the English'. That might piss some people off.

I'm sure some people track these sort of tribal affiliations between inhabitants of the British isles over the course of a millenium, too, but again I'd consider it a silly thing to get riled up about.

I think people tend to care about these things when one nation is subjugated by another, more powerful one, which tends to exert its dominance.

Hence the 'weaker' nation feels deprived of its history when its proudest moments are appropriated away.