Watchmen were organised groups of men, usually authorised by a state, government, city, or society, to deter criminal activity and provide law enforcement as well as traditionally perform the services of public safety, fire watch, crime prevention, crime detection, and recovery of stolen goods. Watchmen have existed since earliest recorded times in various guises throughout the world and were generally succeeded by the emergence of formally organised professional policing.
An early reference to a watch can be found in the Bible where the Prophet Ezekiel states that it was the duty of the watch to blow the horn and sound the alarm. (Ezekiel 33:1-6)
The Roman Empire made use of the Praetorian Guard and the Vigiles, literally the watch.
The streets in London were dark and had a shortage of and poor quality artificial light. It had been recognised for centuries that the coming of darkness to the unlit streets of a town brought a heightened threat of danger, and that the night provided cover to the disorderly and immoral, and to those bent on robbery or burglary or who in other ways threatened physical harm to people in the streets and in their houses.
The anxieties that darkness gave rise to had been met by the formation of a night watch in the 13th century, and by the rules about who could use the streets after dark. These rules had for long been underpinned in London and other towns by the curfew, the time (announced by the ringing of a bell) at which the gates closed and the streets were cleared. Only people with good reason to be abroad could then travel through the city. Anyone outside at night without reason or permission was suspicious and potentially criminal.
Allowances were usually made for people who had some social status on their side. Lord Fielding clearly expected to pass through London's streets untroubled at 1am one night in 1641, and he quickly became piqued when his coach was stopped by the watch, shouting huffily that it was a 'disgrace' to stop someone of such high standing as he, and telling the constable in charge of the watch that he would box him on the ears if he did not let his coach carry on back to his house.