Not that I am a pedantic bastard (ok, I am), but neither Northern Ireland or the Isle of Man are part of Great Britain. Northern Ireland is part of the United Kingdom (of Britain and Ireland), and the Isle of Man is almost an almost entirely self governing part of the British Isles.
I don't really care but a lot of people get pretty pissed off at such distinctions
Being also pedantic, 'Britain' as opposed to 'Great Britain' was accepted in 1975 as a shortened term meaning the 'United Kingdom of Great Britain and Northern Ireland' and the Isle of Man is counted amongst the British Isles. :3