The Serjeant at Arms is responsible for the order and security of the House of Commons. The Serjeant's responsibilities include; maintaining order in the Chamber, galleries, committee rooms and precincts of the House of Commons. The Serjeant also controls the access to the parliamentary estate. The office of Serjeant at Arms goes back to 1415 and the reign of Henry V when the Serjeant was responsible for carrying out the orders of the House of Commons, including making arrests.
Today the Serjeant performs several ceremonial duties that date back to the early days of the office. They carry the mace in the Speaker's Procession each day and also into the House of Lords during the State Opening of Parliament. The Serjeant at Arms is the only person in the House of Commons allowed to carry a sword.
Further information on this subject can be found from the following links.
About Parliament: Serjeant at Arms
Guides to People, Events and Places: Serjeant at Arms ( PDF 404 KB)
Related glossary term: House of Commons departments
Related glossary term: Black Rod (House of Lords)