LONDON, UNITED KINGDOM - JUNE 08: (EMBARGOED FOR PUBLICATION IN UK NEWSPAPERS UNTIL 24 HOURS AFTER CREATE DATE AND TIME) Prince William, Duke of Cambridge and Prince Louis of Cambridge watch a flypast from the balcony of Buckingham Palace during Trooping The Colour, the Queen's annual birthday parade, on June 8, 2019 in London, England. The annual ceremony involving over 1400 guardsmen and cavalry, is believed to have first been performed during the reign of King Charles II. The parade marks the official birthday of the Sovereign, although the Queen's actual birthday is on April 21st. (Photo by Max Mumby/Indigo/Getty Images)