Female sentries are guarding Britain's Queen Elizabeth for the first time at Windsor Castle. The King's Troop of the Royal Horse Artillery took over guarding the queen's residence for one month Monday, and the 20-strong troop includes five women.

They marched led by a brass band wearing plumed busby hats and braided uniform tunics, carrying ceremonial swords.

The King's Troop will provide a 24-hour guard for the palace with sentries on duty for two hours at a time.

A spokesman for the Ministry of Defense said: "Normally, these duties are done by resident infantry battalions in London, but there have been occasions when other units have filled in.

"At the moment one of the units is on its way to Afghanistan and one has just come back from Bosnia so we asked for support from the King's Troop."

In January this year the King's Troop became the first unit to have a female commanding officer when Major Erica Bridge became leader of the 168 officers and troopers.

Bridge's appointment made the unit the first in the 350-year history of the Household Cavalry to be commanded by a woman.

In 2000 four women were among an Australian detachment on guard duty outside Buckingham Palace during Australia week.

Almost 40 percent of the King's Troop - who fire salutes to the queen on state occasions - are now female.