Ooh! Well, with no John Watson, they never got into the Strand, and Lestrade's equivalent in this AU got most of the credit for the actual cases. But he'd be in the newspapers, and locally famous as That Detective Guy that turns up sometimes. So if someone is particularly interested in crime history, they might know him. Sherlock still uses his name because he doesn't mind talking about it if people put two and two together, they just rarely do or they don't like being around him long enough to have that conversation.