Though Detective Jones is a minor character in “The Red-Headed League,” he serves as a subtle foil to Holmes in the story, meaning that his presence in the story (and his juxtaposition with the protagonist) reveals important qualities of Holmes’s character. Specifically, Jones represents the kind of overly confident yet incompetent detectives to whom Holmes is superior.
The following passage—in which Jones speaks about Holmes with the bank owner Merryweather—captures this difference between Jones and Holmes:
“You may place considerable confidence in Mr. Holmes, sir,” said the police agent loftily. “He has his own little methods, which are, if he won’t mind my saying so, just a little too theoretical and fantastic, but he has the makings of a detective in him.”
Here, Jones presents himself as superior to Holmes, pejoratively describing Holmes’s methods as “little” as well as “too theoretical and fantastic,” condescendingly concluding that Holmes at least “has the makings of a detective in him.” Of course, by the end of the story, it is clear that Holmes’s “little methods” are the reason that Clay is captured, while Jones's conventional skill set contributed very little. In fact, while Holmes was able to capture Clay, Jones failed even to apprehend Clay’s accomplice Archie.
By including Detective Jones as a foil character, Conan Doyle is highlighting the incompetence of the English police force in the late 1800s and its need for rational, detail-oriented detectives rather than boastful and ineffective ones.
