Britain's Prince Charles, Prince of Wales (L), Prince William, Duke of Cambridge, (C) and Britain's Princess Anne, Princess Royal, (R) give a salute as they ride during the Queen's Birthday Parade, 'Trooping the Colour,' from Buckingham Palace to Horse Guards Parade in London on June 13, 2015. The ceremony of Trooping the Colour is believed to have first been performed during the reign of King Charles II. In 1748, it was decided that the parade would be used to mark the official birthday of the Sovereign. More than 600 guardsmen and cavalry make up the parade, a celebration of the Sovereign's official birthday, although the Queen's actual birthday is on 21 April. AFP PHOTO / BEN STANSALL (Photo credit should read BEN STANSALL/AFP/Getty Images)
