Michael Sims starts his sprightly disquisition on the origins of Sherlock Holmes with the familiar story of Joseph Bell, senior surgeon at Edinburgh’s Royal Infirmary in the late 19th century. One day in around 1880 a visitor tells Bell that he is at the hospital seeking treatment for elephantiasis. Bell responds by showing off his well-honed consultation technique. He correctly surmises that, based on various visual and other clues, the man had, until recently, served as a non-commissioned officer in a Highland regiment and been stationed in Barbados. Why that in particular? Because elephantiasis was endemic in the West Indies. Bell could tell he’d been in the military because, although respectful, he hadn’t taken off his hat on entering the room.

This story is related by Arthur Conan Doyle in his autobiography, Memories and Adventures, where he identifies Bell, his former teacher in the medical school at Edinburgh University, as the model for Sherlock Holmes. Since then it has cropped up regularly in books about Conan Doyle and Sherlock,