The Metropolitan Police Service (MPS), commonly known as the Metropolitan Police and informally as the Met, is the territorial police force responsible for law enforcement in Greater London, excluding the "square mile" of the City of London, which is the responsibility of the City of London Police.
The Met also has significant national responsibilities, such as co-ordinating and leading on UK-wide national counter-terrorism matters, and the protection of the senior members of the British Royal Family, and also members of The Cabinet and other ministerial members of Her Majesty's Government.
As of September 2017, the Met had 40,874 full-time personnel. This included 30,871 police officers, 8,005 police staff, 1,384 police community support officers and 614 designated officers. This number excludes the 2,470 special constables, who work voluntarily part-time (a minimum of 16 hours a month) and who have the same powers and uniform as their regular colleagues. This makes the Metropolitan Police, in terms of officer numbers, the largest police force in the United Kingdom by a significant margin, and one of the biggest in the world. In terms of its police area (primary geographic area of responsibility), leaving its national responsibilities aside, the Met has the 8th smallest police area of the territorial police forces in the United Kingdom.
The overall operational leader of the force is the Commissioner, whose formal title is Commissioner of Police of the Metropolis. The Commissioner is answerable, responsible and accountable to The Queen, the Home Office and the Mayor of London, through the Mayor's Office for Policing and Crime. The post of Commissioner was first held jointly by Sir Charles Rowan and Sir Richard Mayne. Since April 2017 the post is occupied by Cressida Dick.
A number of informal names and abbreviations are applied to the Metropolitan Police Service, the most common being the Met. In colloquial London (or Cockney slang), it is sometimes referred to as the Old Bill. The Met is also referred to as Scotland Yard after the location of its original headquarters in a road called Great Scotland Yard in Whitehall. The Met's current headquarters is New Scotland Yard, situated on the Victoria Embankment.
The Metropolitan Police Service, whose officers became affectionately known as "bobbies", was founded in 1829 by Robert Peel under the Metropolitan Police Act 1829 and on 29 September of that year, the first units of the service appeared on the streets of London. In 1839, the Marine Police Force, which had been formed in 1798, was amalgamated into the Metropolitan Police. In 1837, it also incorporated with the Bow Street Horse Patrol that had been organised in 1805.
Since January 2012, the Mayor of London is responsible for the governance of the Metropolitan Police through the Mayor's Office for Policing and Crime (MOPAC). The mayor is able to appoint someone to act on his behalf; the current office-holder is Deputy Mayor for Policing and Crime, Sophie Linden. The work of MOPAC is scrutinised by the Police and Crime Committee (also known as a police and crime panel) of the London Assembly. These structures were created by the Police Reform and Social Responsibility Act 2011 and replaced the Metropolitan Police Authority appointed board created in 2000 by Greater London Authority Act 1999.