Not sure what you mean by "along the lines of Sherlock Holmes..." but the following authors are all British, all their sleuths are amateurs (as opposed to professional police investigators), and they all take place in the 1860-1930 time frame.
Charles Finch - investigator Charles Lenox, who has a Dr. Watson-like sidekick.
Susan Elia Macneil - investigator Maggie Hope, works undercover in the British government during wartime.
Tasha Alexander - investigator Lady Emily Hargreaves, rich noblewoman who "assists" her government agent spouse.
Dorothy L. Sayers - investigator Lord Peter Wimsey
Emily Brightwell - investigator Mrs. Jeffries, who leads the household staff of a police inspector in helping him to solve his cases.
Jacqueline Winspear - inspector Maisie Dobbs, a psychologist who started out as a downstairs maid.
The Emily Brightwell series is kind of "fluff," but the stories are entertaining. All the others are pretty serious mysteries with engaging characters and interesting plots.
I could do more research, but I've read all these authors recently, so they came easily to mind. Hope this helps.
Queen Colleen