The Last Man
Winston?
O'Brien calls Winston the last man when Winston is the only person that fully knows both worlds but chooses to be a good guy. This is being said because others that understand both worlds choose power over doing the right thing. You can't be called the last man and not have the correct knowledge of both worlds. They only know the world of being strict and the world of everything they hear is automatically true without any information that can prove the statement wrong. Winston is what we call a very unique man and that's why he is trying to change things