Poe's Dupin made his first appearance in an 1841 short story, The Murders In The Rue Morgue, followed by The Mystery Of Marie Roget (1842) and The Purloined Letter (1845). There are many similarities between Dupin and Holmes. Dupin is an upper-class amateur detective, who views his work as an exact science, and looks down on the plodding Parisian police. When he has no case to solve, he relapses "into his old habits of moody reverie".  As in the Holmes stories, Poe's tales are narrated by the detective's less brilliant housemate.

Dupin has a wealth of out-of-the way knowledge. Thanks to his familiarity with zoology, he concludes that the killer of two women in the Rue Morgue is not a human at all, but a "large fulvous Ourang-Outang of the East Indian Islands". Doyle's detective would be similarly expert, writing monographs on subjects as varied as the 140 different types of tobacco ash, the anatomy of the human ear, and the 16th century composer, Lassus.

Poe's detective has the ability to read his partner's mind, following his unspoken thoughts by changes in his facial expressions, and then breaking in with an appropriate remark. Discussing Dupin with Watson in A Study In Scarlet, Holmes disparages this trick as "very showy and superficial". Yet Doyle could not resist making Holmes perform the very same trick with Watson in a later short story, The Resident Patient.

In 1894, a reporter asked Doyle if he had been influenced by Poe's Dupin. He replied, "Oh immensely! His detective is the best detective in fiction!" When the reporter asked if he included Holmes in this assessment, Doyle said, "I make no exception. Dupin is unrivalled."

Inspector Bucket

The first English writer to choose a detective theme was Charles Dickens, whose Inspector Bucket tracks down a murderer in Bleak House (1853). Bucket, a minor character in the novel, is a dependable middle-class policeman, who solves the case by dogged persistence rather than brilliant reasoning. His single-minded pursuit of criminals is symbolised by his "fat forefinger" which has a life of its own:

"When Mr. Bucket has a matter of this pressing interest under his consideration, the fat forefinger seems to rise, to the dignity of a familiar demon. He puts it to his ears, and it whispers information; he puts it to his lips, and it enjoins him to secrecy; he rubs it over his nose, and it sharpens his scent; he shakes it before a guilty man, and it charms him to his destruction... Mr. Bucket pervades a vast number of houses and strolls about an infinity of streets... He is free with his money, affable in his manners, innocent in his conversation -but through the placid stream of his life there glides an under-current of forefinger."

Sergeant Cuff

In 1868, Dickens's friend Wilkie Collins placed a police detective, Sergeant Cuff, at the centre of his novel, The Moonstone. Collins follows Poe in presenting readers with a mystery, which the detective must solve - in this case the theft of an enormous diamond in a country house. All the evidence is placed before the readers, giving them the impression that they too could solve the mystery. There are many likely suspects, including a hunchbacked housemaid and a troop of Indian jugglers, all interviewed by Sergeant Cuff before he finally reveals the true culprit.

Bucket and Cuff are Victorian policemen, men who were viewed as public servants, and whose power derives from their membership of a great organisation. They are both conservative men, deferential to their social superiors. When Arthur Conan Doyle wanted to create his own detective, he went back to the earlier model of Poe's brilliant amateur detective. Doyle saw that the amateur provided the best opportunity to create a vivid individual character.