One of those little points of Sherlock Holmes's past that fascinates me whenever I return to it comes in "The Musgrave Ritual."
"Even when you knew me first, at the time of the affair which you have commemorated in 'A Study in Scarlet,' I had already established a considerable, though not a very lucrative, connection," Sherlock Holmes explains to Dr. Watson.
The singular form of that word always evokes the thought of a single source of income. Later, when we encounter Watson using the word himself, it takes on a different cast:
"Shortly after my marriage I had bought a connection in the Paddington district. Old Mr. Farquhar, from whom I purchased it, had at one time an excellent general practice; but his age, and affliction of the nature of St. Vitus's dance from which he suffered, had very much thinned it."
Watson, of course, is talking about a base of regular patients, as any medical practice has. And we know that Sherlock Holmes's career of "consulting detective" is based upon the model of a medical specialist. But does a detective have enough regular customers to maintain a practice like a doctor? Who would such folk be, that had mystery after mystery in their lives?
Well, Scotland Yard comes quickly to mind, and if CBS's Elementary and many another TV procedural is to be believed, major metropolitan police forces just love returning to non-cops for help. Heck, in one Fox-now-Netflix show, the police like hitting up the devil himself for help in solving their cases. But the Sherlockian Canon is a little more sophisticated than those shows, and Holmes's client list is a lot more varied.
Did Holmes have a sign outside his Montague Street rooms, announcing he was open for business to walk-in trade? Did he advertise in the papers, perhaps something small in the personal section?
Was his main income coming from family money, or, as Holmes was as much artist as doctor, did his "connection" come from a single wealthy patreon, who used his services occasionally and liked to have a consulting detective on retainer. We know, also from "The Musgrave Ritual," that some of Sherlock's early cases came from those he met at college, like Reginald Musgrave. Wealthy young men who could afford to hire such services from the day they left college. Might such a patreon have come from that pool? Or maybe an old family friend who took at interest in Holmes's unique attempt at vocation?
We never hear of Scotland Yard paying Holmes in the Canon, but we do get a good look whenever he can get a payday off someone with wealth. And Scotland Yard does send people his way, so that may have been the currency they paid him in . . . supplying him with clients rather than cash in exchange for help on high-profile cases they couldn't just pawn off on him. That would have been a great connection for Holmes to make, and it's the one he explains to Watson early on.
"Here in London we have lots of Government detectives and lots of private ones. When these fellows are at fault they come to me, and I manage to put them on the right scent," Holmes explains at first, but when Watson questions him about his non-white-male-police-looking clients, Holmes adds, "They are mostly sent on by private inquiry agencies. They are all people who are in trouble about something, and want a little enlightening. I listen to their story, they listen to my comments, and then I pocket my fee."
Note that there was no mention of that fee when he was speaking about Lestrade and the other detectives just a moment before. One suspects Sherlock Holmes just enjoyed beating them at the game, but getting them to send along their problem cases was surely his best "connection" to them, even if, as he says in "Musgrave Ritual," not "very lucrative."