Holmes’s methods—baffling to Watson—are well known to modern-day costume curators and conservators. “We are quite Sherlockian in our approach,” Long says. “We regularly look at wear marks, labels, and types of materials.” Inspired by the Holmes stories, Long and “an army of volunteers” scoured the museum’s archives for historical garments with tell-tale clues to the wearer’s identity. A pair of men’s evening shoes on display has circular wear marks on the soles, suggestive of dancing; a woman’s blouse with ink-stained sleeves recalls the one that helped Holmes identify his client as a typist in A Case of Identity.

A master of disguise, Holmes had an arsenal of unlikely alter egos, from an old lady to a “simple-minded Nonconformist clergyman.” Long notes that although Holmes’s borrowed makeup and wardrobe techniques from the Victorian stage, his disguises were not particularly theatrical or exotic, but “the disguises of the everyday.” In Sherlock, Cumberbatch has convincingly posed as a French waiter, a Guardsman, a hoodie-clad heroin addict, and a Pakistani terrorist.