This is a collection of thirteen stories written by English authors from the years 1891 to 1914. The editor of the collection is Hugh Greene, brother of Graham. Hugh Greene seems to have collected old mysteries and, since he worked in television, this collection was a basis for a British television series (which I haven't seen.)
Greene says he limited the selection of mysteries to characters who had an identifiable London address, like 221B Baker Street. But they're not all consulting detectives. Some are; but Lady Molly is with Scotland Yard; the Old Man in the Corner solves crimes for his own amusement, but doesn't worry about bringing the criminal to justice; Mr. Pringle is a con man; and Simon Carne is simply a thief.
I think we can safely say that Sherlock Holmes actually doesn't have any rivals... ;-) but some of these are nevertheless fun. I particularly liked the two by Baroness Orczy, better known as the author of The Scarlet Pimpernel. But her stories about Lady Molly and The Old Man in the Corner are quite good. Also good was R. Austin Freeman's Dr. Thorndyke story, and Ernest Bramah's story about Max Carrados, the blind detective. Several of these detectives are represented on the Haycraft-Queen list of classic mysteries.
And because they're early, a bunch of these are available at Project Gutenberg, and I'd previously read the first collection of Old Man in the Corner stories and the collection of stories about Max Carnacki, the ghost finder, by William Hope Hodgson.