WINDSOR, ENGLAND - MAY 15: Prince William, Duke of Cambridge 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: Prince William, Duke of Cambridge 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 )
