WINDSOR, ENGLAND - MAY 15: Queen Elizabeth II and Prince Philip, Duke of Edinburgh at The Queen's 90th Birthday Celebration at The Royal Windsor Horse Show on May 15, 2016 in Windsor, England. (Photo by Mark Cuthbert/UK Press via Getty Images )
WINDSOR, ENGLAND - MAY 15: Queen Elizabeth II and Prince Philip, Duke of Edinburgh at The Queen's 90th Birthday Celebration at The Royal Windsor Horse Show on May 15, 2016 in Windsor, England. (Photo by Mark Cuthbert/UK Press via Getty Images )