
When I was nineteen, I briefly shared a flat with a young lesbian couple who liked to go to parties dressed as Sherlock Holmes and Dr Watson. They accessorised with moustaches and dapper little hats and their own interpretation of what went on at Baker Street after Mrs Hudson had retired to bed. I had read and loved Arthur Conan Doyle’s stories as a kid. It was these girls, though, who taught me what fannishness could really mean – loving a story so hard, so shamelessly, that you let it change you, and maybe you change it in turn.
Some years later, I lived just off Baker Street, and walked to work past the Sherlock Holmes Hotel (complete with “Watson Burger” for American pilgrims) and a tube station plastered with tile profiles of a familiar figure with a deerstalker and pipe. The line between “fan fiction” and actual fiction has always been fuzzier than people wanted to admit – and the many worlds of Sherlock Holmes bear that out, none more so than the recent BBC “re-imagining”, now in its third series. It is possible that no showrunners have ever been more gleefully fannish than Mark Gatiss and Steven Moffat.