Poisoned Pen Press, it's 352 pages and available in ebook and paperback formats. Editor Martin Edwards provides erudite, interesting commentary and an introduction for each of the stories.
The stories themselves are classic and varied. There's a canonical Holmes and Watson short, a Raffles story, as well as stories by luminaries of the genre including Edmund Crispin, Josephine Bell, C.S. Forester (Horatio Hornblower), and others. Honestly, the author list reads like a who's who of classic and golden age mystery fiction. The commentary and introduction are also top rate. I always learn something from Mr. Edwards' vast storehouse of mystery history; this time it was that E. W. Hornung (Raffles) was also Sir Arthur Conan Doyle's brother in law!
These are wonderful old stories. They mostly still play very well to a modern readership and all of these are worthy of preservation and publishing for new generations of mystery lovers.
Well done! Five stars.
Disclosure: I received an ARC at no cost from the author/publisher for review purposes.