LONDON, UNITED KINGDOM - MARCH 17: (EMBARGOED FOR PUBLICATION IN UK NEWSPAPERS UNTIL 48 HOURS AFTER CREATE DATE AND TIME) Catherine, Duchess of Cambridge presents a shamrock to Irish Wolfhound 'Domhnall' (Mascot of the Irish Guards) as she attends the annual St Patrick's Day Parade at Cavalry Barracks on March 17, 2017 in London, England. (Photo by Max Mumby/Indigo/Getty Images)

LONDON, UNITED KINGDOM - MARCH 17: (EMBARGOED FOR PUBLICATION IN UK NEWSPAPERS UNTIL 48 HOURS AFTER CREATE DATE AND TIME) Catherine, Duchess of Cambridge presents a shamrock to Irish Wolfhound 'Domhnall' (Mascot of the Irish Guards) as she attends the annual St Patrick's Day Parade at Cavalry Barracks on March 17, 2017 in London, England. (Photo by Max Mumby/Indigo/Getty Images)