Who is Black Rod and what is their job in the House of Lords?

The first female Black Rod has been appointed in 650-year history of the House of Lords.

Sarah Clarke, who is Championships Director for the All England Lawn Tennis Club, will take on the role next year when current post holder David Leakey steps down.

But what is the historic post?

Black Rod is a senior official in the House of Lords, who is responsible for maintaining order and organising ceremonial events within the Palace of Westminster.

The name derives from the three and a half foot ebony staff that the post holder carries, which is topped with a golden lion to symbolise the power of the office.

As the Queen's representative in Parliament, Black Rod's most high-profile ceremonial job is to summon MPs to listen to the Queen's Speech in the Lords during the state opening of Parliament.

In a symbol of the Commons' independence from the monarch, the doors of the Chamber are slammed in Black Rod's face before they strike the door three times with the ebony staff.

MPs then follow Black Rod to the Lords, dawdling and talking loudly, to hear the monarch outline the Government's legislative programme.

As well as the ceremonial duties, Black Rod is responsible for organising access to and maintaining order within the Lords Chamber and the precincts, and is responsible for the Queen's residual estate in the Palace and the Chapel of St Mary Undercroft.

The earliest known reference to the role of Black Rod as the Usher to the Order of the Garter appears in letters in 1361. Walter Whitehorse is believed to have been the first person to hold the post, which 59 others have held since.

David Leakey, a former army commander, has been in the post since 2010.

The first reference to Black Rod in connection with Parliament comes in a Garter statute of 1522 which states that Black Rod has an additional duty to "keep the doors... in the High Court called Parliament".

It is thought that, when Henry VIII moved from the Palace of Westminster to the Palace of Whitehall, Black Rod - a member of the Royal Household, stayed behind to act as usher to the House of Lords.

There are also Black Rods in the parliaments and legislative assemblies of Canada, Australia and New Zealand.