It's correct name is the Royal Standard, and the figures that tamborine gave relate to the size of the palace, not the standard. See this website for dimensions of the Royal Standard:
http://www.thamesweb....lagsandflagstaff.html
Size doesn't matter to me tony. It's how you handle it that counts! (did I really say that?) Anyway I asked the question because my OH and I are watching the coverage on BBC and I just wondered how big it was.