Britain's Prince William, Duke of Cambridge, (front row 3L) and his wife Britain's Catherine, Duchess of Cambridge (front row 3R) pose for a photograph with rmembers of the 1st Battalion Irish Guards, during their annual St Patrick's Day parade at Cavalry Barracks in Hounslow, west London on March 17, 2017. / AFP PHOTO / POOL / RICHARD POHLE        (Photo credit should read RICHARD POHLE/AFP/Getty Images)