Every hit detective show needs a double act. Now the true story of Henry and Sir John Fielding, the crime-fighting magistrate brothers who created Britain’s first police force, is being turned into a series.

Eighteenth century London was a violent den of brothels, murderers and street gangs. It fell to Henry Fielding, the author of the novel Tom Jones, and his half-brother Sir John, a leading social reformer, to bring order to the streets.

In 1749 Parliament permitted the magistrate brothers to put together a small crime-fighting force to clean up London.

The story of the Bow Street Runners and the real cases they investigated is brought to life in City of Vice, a primetime Channel 4 series which aims to reinvent the classic “cop show” by returning to the source material.

The Fielding brothers, played by Ian McDiarmid and Iain Glen, could prove as popular a crime-fighting duo as The Sweeney’s Regan and Carter or Morse and Lewis.

The success of Life on Mars, the BBC time-travel series which transported a modern-day detective to the 1970s, demonstrated a viewer appetite for historical crime shows.

City of Vice opens with Jack Harris, the “Covent Garden pimp” and author of a notorious guide to the capital’s prostitutes, drawn into an investigation over a series of horrific rapes.

Hallie Rubenhold, historical consultant, said: “Eighteenth century London was much more dangerous than today and no one was completely safe from crime.

“The very wealthy rarely went anywhere without their servants who often acted as the first line of defence against crimes of violence.

“The very poor parts of London were virtually lawless. Covent Garden with its numerous drinking establishments was the sight of many murders throughout the era and the ill-lit streets were ideal hiding places for pickpockets and gangs of robbers.”

Sir John Fielding, blinded in a navy accident at the age of 19, was known as “Blind Beak of Bow Street”, where he succeeded his brother as Chief Magistrate.

“Thief-takers”, who solved crimes for cash, had been the only protection for the innocent. Sir John and Henry faced great opposition when they called for the creation of a state-funded body to control the streets.

Clive Bradley, writer of the Touchpaper Television series, said: “It was a very idealistic project. The brothers thought they could eliminate crime in a few years and the whole idea of creating a police force was extremely radical at the time.”

Like contemporary TV cops, the brothers were not averse to roughing up suspects to get results. The series portrays them employing torture techniques.

Mr Bradley said: “Although Sir John was a radical up to a point, he was no revolutionary — part of his aim in founding the police was to protect property, most of which belonged to the upper classes.”

Based on Henry Fielding’s diaries and contemporary sources such as the Old Bailey Sessions Papers, City of Vice is designed to provide a lurid counterpoint to rival period dramas.

Iain Glen, (John Fielding), said: “When we do dramas on TV we go sort of fluffy and Jane Austen-y, and it’s nice, easy viewing. This is the murkier, sordid truth of how most people actually lived at that time.”

The Bow Street Runners, who travelled across Britain to arrest rogues, were credited with providing a blueprint for the Metropolitan Police Force, established by Sir Robert Peel in 1829. Bow Street Magistrates’ court, in Covent Garden, closed in 2006, under plans to convert the site into a boutique hotel.

City of Vice, which begins next week, will compete with the BBC One sequel to Life On Mars. In Ashes To Ashes, the partnership of the irascible DCI Gene Hunt and Sam Tyler has been broken up.

The action is transported to riot-torn London in 1981 where the unreconstructed Hunt (Philip Glenister) is paired with an independent-minded young female detective, played by Keeley Hawes.

City of Vice begins Monday 14 January, Channel 4, 9pm.

Editor's choice

• The 100 Best Films of the Decade
• 70 facts you didn't know about Marvel
• The 50 Biggest Movies Of 2010