The Yeomen of the Guard make up the oldest military corps still in existence, created by Henry VII in 1485 at the Battle of Bosworth Field.
Officially, they are a bodyguard of the British Monarch, but their duties are now purely ceremonial.
There are 60 Yeomen of the Guard, drawn from retired members of the Army, Royal Marines and RAF - and they still don Tudor dress when on duty.
In Parliament, the Yeomen of the Guard carry out a ceremonial search of the cellars of the Houses of Parliament prior to the state opening of Parliament, in a tradition that dates back to the time of the Gunpowder Plot.
The Captain of the Yeomen of the Guard is a government post, usually held by the Deputy Chief Whip of the House of Lords.