Well, that is definitly a British Martini-Henry or at least a Martini "short lever" action, I know THAT much just by looking at it
ANY Martini action will have SOME value to a collector, and I know there IS collector interest in them. Yours seems to be a rare model, too, so it would probably be worth a premium, or a little more than another "typical" .22 Martini, I would guess anyway. I DO know you could get that action chambered in just about any cartridge, it was pretty much a contemporary of, and as strong and accurate, and as popular as, the Remington Rolling Block was at the same time.
The Martini in various calibers, usually .450 to .500, usually black powder big bores, was the main rifle of the British army in the late 1800s almost until 1900.
Unfortunately I'm NOT a Martini collector, but somebody here will come along with some answers.
However I LOVE to research, and I have a few good gun refernce books laying around, so I will start digging and see what I can find.
You MIGHT get lucky doing a Google search on "Martini .22" or "Martini-Henry .22" or even just 'Martini-Henry." You MIGHT just get directed to a Martini site that will have answers.
You can do it from the bottom of this page too.