WINDSOR, ENGLAND - APRIL 20: Queen Elizabeth II visits the Queen Elizabeth II delivery office in Windsor with Prince Philip, Duke of Edinburgh on April 20, 2016 in Windsor, England. The visit marks the 500th Anniversary of the Royal Mail delivery service. The Queen and Duke of Edinburgh are carrying out engagements in Windsor ahead of the Queen's 90th Birthday tommorow. (Photo by Chris Jackson - WPA Pool/Getty Images)
