I just watched the 1931 film The Speckled Band, starring a young Raymond Massey as Sherlock Holmes. Massey would later find fame playing Dr. Kildare on television, but is also known to mystery lovers as Jonathan Brewster (the Boris Karloff stand-in) in Arsenic & Old Lace.
This film is a curiosity. It is mostly a (relatively) faithful adaptation of the story, but seems to be taking place in two different eras. The scenes at the Rylott appear to be set in the Victorian Era, including fashions, while the London is definitely in the 1930s, with Holmes maintaining an office full of state-of-the-art 30s office machinery and a staff of secretaries and stenographers (!). In this sense, the film presages the Basil Rathbone modern era films.
The acting is a mixed bag. Massey's Holmes feels more Philo Vance than Sherlock. Athole Stewart is a forgettable generic Watson (but no buffoon, so he has that going for him). Angela Baddeley plays Helen Stonor like a rabbit perpetually caught in the headlights. The film's saving grace is Lyn Harding as a superbly villainous and threatening Dr. Grimesby Rylott.
I can't say I really recommend it, but it is an interesting curio. If not the first Holmes talkie, it must be one of the early ones. And with a running time of just over an hour, it is worth a watch if you have some time to kill and are interested in the evolution of the screen Holmes.
And your bonus trivia: Raymond Massey was Jeremy Brett's father-in-law. Brett was married to Massey's daughter Anna from 1958 to 1962.