Donning a dark green coat, Kate also greeted a tall Irish wolfhound and mascot Domhnall.
LONDON - Britain's Prince William and his wife Kate kicked off St Patrick's Day celebrations in London on Sunday as they observed a parade of the 1st Battalion Irish Guards and Kate presented a shamrock to its officers.
From Galway to New York, events are being held across countries with parades and parties to mark Ireland's National Day, when revellers traditionally dress in green.
Donning a dark green coat, Kate also greeted a tall Irish wolfhound and mascot Domhnall while William, dressed in full military attire, took the salute during a march past.
William, the grandson of Britain's Queen Elizabeth and second in line to the throne, is colonel of the Irish Guards, a regiment of the British army.
The couple will later meet members of the regiment and attend a lunch. Events will be held across London to celebrate the day.