"Re Mrs Hudson's Diaries: A view from the landing at 221b (In Brief, February 8): a mistake made in every post-Conan Doyle book, film and TV portrayal of Sherlock Holmes. 221 Baker Street was built as a large family house, but its function was overtaken by social change, and became economically viable only as sets of rooms, let floor by floor. 221b was thus the first-floor lodging of Holmes and Watson, 221a the ground-floor set of rooms, while the housekeeper, Mrs Hudson, lived in the basement. The house remained plain no 221.
Castello 639, Venice."
—This is why the letters section of the Times Literary Supplement is one of the few things left in this broken, hopeless world that brings me anything even approaching joy. Anyway, none of you should ever make this mistake again! Also, the book looks kind of entertaining, if that's the sort of thing you're into.