The point I'm making is, British what?  A British citizen (I agree).  But ethnically, culturally, etc, may be something else - Indian, Irish, Italian, etc.  The infobox arguments could all go away if they removed "Nationality" and replaced it with "Citizenship", which removes all self-identification issues and simply comes down to which passport is held.  Although invariably, somebody would want to add another box to indicate the self-identified nationality I'm sure...