LONDON - Hundreds of soldiers in scarlet tunics and bearskin hats marched in London Saturday to celebrate the official birthday of Queen Elizabeth II.

The 84-year-old monarch wore a lilac outfit and matching hat as she inspected ranks of soldiers as part of a ceremony known as Trooping the Color, in which a regiment's flag is paraded past soldiers and the monarch.

The 1,400 soldiers on parade -- with drums, marching bands and more than 200 horses -- were members of the Household Division, which is assigned to guard the monarch, alongside other duties. They included members of 1st Battalion Grenadier Guards, who returned from deployment in Afghanistan six weeks ago.

Later the queen, her husband Prince Philip and other members of the royal family watched a fly-over of military aircraft from a balcony at Buckingham Palace, as thousands of tourists and well-wishers gathered below.

The queen's birthday is celebrated twice a year -- privately on April 21, her actual birthday, and again with an official national celebration in June.

British monarchs have been publicly celebrating their birthdays in June since the 18th century, in hope of good weather for public events.