LONDON, ENGLAND - JUNE 13:  Prince George looks through a window in Buckingham Palace prior to the Trooping The Colour ceremony on June 13, 2015 in London, England. The ceremony is Queen Elizabeth II's annual birthday parade and dates back to the time of Charles II in the 17th Century, when the Colours of a regiment were used as a rallying point in battle.  (Photo by Chris Jackson/Getty Images)