Tradition is something that the Royal Family takes very seriously. Without tradition, there would in effect be no Royal Family to speak of. They exist because they've always existed and because no one seeks to challenge to status quo.
At least, no one ever did — until Princess Diana came along. During her short tenure as a member of the Royal Family, she upended and defied tradition as she saw fit. So in order to celebrate her for the trailblazer that she was, here is every time Princess Diana broke Royal protocol.