Claims to fame are
1) Ninth biggest island in the world!
2) One of the most populous islands in the world!
3) One of the few islands of significant size that officially calls itself 'great'!
4) One of a series of islands which governed massive empires!
My main family line comes from Great Britain (from what I can tell well established and probably pre-Norman Dane) so please do not believe I am mocking British with this post. I am amused by the BBC's need to justify Britannia.