Sherlock Holmes was based on a real-life investigator
Jasper Copping, in London, on the detective with remarkable similarities to Arthur Conan Doyle's fictional hero
He enthralled Victorian England with his unrivalled skill at cracking cases, based on astute reasoning and grasp of forensic science, not to mention a mastery of disguises and encyclopedic knowledge of the criminal underclass.
However, this detective was not Sherlock Holmes but a real-life investigator, Jerome Caminada, who, research suggests, was the main inspiration for Arthur Conan Doyle's celebrated hero.
A biography of Caminada reveals a series of striking similarities between him and the fictional character. It also finds strong echoes of the real detective's cases in plot lines used by Doyle.
The author, Angela Buckley, established that Caminada's work involved tackling an alluring criminal, similar to Irene Adler, and that the detective had a Moriarty-like nemesis who plagued him until a final confrontation.
Mrs Buckley said: "Caminada became a national figure at just the time that Holmes was being created. There are so many parallels that it is clear Doyle was using parts of this real character for his."
The son of an Italian father and an Irish mother, Caminada was based in Manchester and rose to prominence in the mid-1880s, shortly before Holmes made his debut in A Study in Scarlet.
As the fictional character relied on a network of underworld contacts – the Baker Street Irregulars – so Caminada was known for his web of informers, whom he would meet in the back pew of a church. These characters helped him build up a deep knowledge of the criminal fraternity, among whom he would often move in disguise – another tactic in common with Holmes, who is played, in his most recent reincarnation, by Benedict Cumberbatch.
Like his fictional counterpart, Caminada prowled the streets alone at night, fearlessly intervening in crimes. His skill with disguises was such that on one occasion, while tracking thieves at the Grand National, his own chief constable was unable to recognise him.
Over his career, he was reportedly responsible for the jailing of 1,225 criminals. His most famous case – and perhaps the one which most closely resembles a Holmes story – was the "Mystery of the Four-Wheeled Cab".
Two men had taken a horse-drawn cab. On the journey, one leapt out and the other was found dying inside. There was no obvious cause of death and few clues, but through a series of deductions, Caminada identified the culprit as Charles Parton, who had drugged the man before getting into the cab to rob him.
Mrs Buckley, a family historian and trustee of the Society of Genealogists, identifies Caminada's "Moriarty" figure as Bob Horridge, a career criminal, with whom he had a 20-year feud, which began when Caminada caught him for stealing a watch. As Horridge was sent down, he swore revenge on the detective.
On his release, Horridge's criminal enterprises grew in size but he stayed one step ahead of the authorities, often effecting dramatic escapes.
His spree finally ended after he shot two police officers. Caminada tracked him to Liverpool where the detective apprehended him after pulling out his revolver faster than the criminal.
Caminada's "Irene Adler" was Alicia Ormonde, an apparently well-educated woman with an aristocratic background and expensive tastes, who was in truth a consummate forger wanted for a string of frauds and thefts.
Caminada arrested her, but – in an echo of Holmes's fascination with Adler – apparently became captivated by her. The case took place in 1890, a year before Adler appeared in A Scandal in Bohemia.
Caminada, who published his memoirs on retiring, died in 1914, the year the last Holmes book was set.
Doyle himself said he had been inspired by Dr Joseph Bell, a surgeon at the Royal Infirmary of Edinburgh for whom Doyle had worked as a clerk. Sir Henry Littlejohn, a former police surgeon, is also cited as an inspiration.
However, Mrs Buckley believes that Caminada was used to give Holmes a better grounding in casework among the criminal fraternity, inspiring his detecting styles and some of the baffling cases he encountered.