Until the middle of the 18th century there was no police force operating in London. General law and order was maintained by magistrates, volunteer constables, watchmen and where necessary the armed forces. If a victim of crime wished to pursue an offender they could employ a "thief taker" who earned a living from such payments and, in the case of notorious offenders, the rewards offered by the courts. The novelist Henry Fielding was appointed a magistrate in Westminster in 1748. His house at No. 4 Bow street had been established as a courtroom in 1739 by the previous owner Sir Thomas de Veil. Fielding brought together eight trustworthy constables, who came to be known as the Bow Street Runners, and gave them the authority to enforce the decisions of magistrates. Fielding's blind half brother Sir John Fielding (known as the "Blind Beak of Bow Street") succeeded his brother as magistrate in 1754 and refined the patrol into first truly effective police force for the capital.
By 1792 salaried constables were been paid by local magistrates and 1798 saw the establishment of the Marine Police a private body based in Wapping to organised primarily to police the docks and prevent the theft of cargo.
During the early 19th century, the industrial revolution saw London becoming a much larger city. It became clear that the system locally maintained constabulary was ineffective in the prevention and detection of crime amongst such a large population. In 1829, The Metropolitan Police Act was passed by the House of Commons. The act placed the policing of the capital directly under the control of the Home Secretary. The initial force consisted of around 1,000 men with instructions to patrol the streets within seven mile radius of Charing Cross in order to prevent crime and pursue offenders.
The head of the Metropolitan Police Service is the Commissioner. The post was first appointed jointly to Colonel Sir Charles Rowan and Sir Richard Mayne. The post is currently held by Sir John Stevens.
The failure of the Met to properly investigate the 1993 racist murder of Stephen Lawrence severely damaged relations with the British Afro-Caribbean community, and lead to the Met being labeled institutionally racist.