A week or so after moving into 221B Baker Street, Watson observes that his fellow lodger Sherlock Holmes receives visits from ‘many acquaintances, and those in the most different classes of society’. Among these visitors, Watson is introduced to a ‘little sallow, ratfaced, dark-eyed fellow … who came three or four times in a single week’ (Study, 17). This is a Mr Lestrade, whom Holmes later reveals to be ‘a well-known detective’ who ‘got himself into a fog recently over a forgery case’ (20). Lestrade would go on to appear, or at least be mentioned, in a further twelve stories, making him the most frequently trans-textual character in the saga apart from Holmes and Watson themselves, and possibly Holmes's landlady Mrs Hudson.

Holmes's patronising reference to Lestrade being in a fog is characteristic of his attitude to police officers, at least in the early stories. Lestrade may be dim, but his dimness reflects that of Scotland Yard as a whole. When in A Study in Scarlet he is invited by Lestrade's colleague Tobias Gregson to attend the crime scene at 3 Lauriston Gardens, Holmes comments: ‘Gregson is the smartest of the Scotland Yarders … he and Lestrade are the pick of a bad lot. They are both quick and energetic, but conventional – shockingly so. They have their knives into one another, too. They are as jealous as a pair of professional beauties. There will be some fun over this case if they are both put upon the scent’ (24). Scent implies the two detectives are like dogs, but Watson's imagery is more demeaning. Having been ‘rat-faced’ in Baker Street, at the scene of Enoch J. Drebber's murder Lestrade becomes ‘lean and ferret-like’ (28). Both he and Gregson are literally clueless (‘“There is no clue!” said Gregson … “None at all”, chimed in Lestrade’), but Lestrade becomes ‘pompous and self-satisfied’ when he discovers the word ‘RACHE’ at the scene. Characteristically, Lestrade turns his triumph into failure as he misinterprets the word – ‘it means the writer was going to put the female name Rachel, but was disturbed before he or she had time to finish’, prompting ‘an explosion of laughter’ from Holmes (31).