LONDON, ENGLAND - MARCH 17: Catherine, Duchess of Cambridge and Prince William, Duke Of Cambridge attend the annual Irish Guards St Patrick's Day Parade at Household Cavalry Barracks on March 17, 2017 in London, England. (Photo by pool/ Anwar Hussein/WireImage)

LONDON, ENGLAND - MARCH 17: Catherine, Duchess of Cambridge and Prince William, Duke Of Cambridge attend  the annual Irish Guards St Patrick's Day Parade at Household Cavalry Barracks on March 17, 2017 in London, England.  (Photo by pool/ Anwar Hussein/WireImage)