Steam Enthusiasts- Can Anyone Help Me to Identify This Antique Boiler?

My partner passed away recently; he was a hoarder and collector of curio, and I've inherited an enormous amount of stuff. Much as it pains me I simply have to sell some of it as I am soon to be evicted and there is far more than I can possibly keep. One item of particular interest is this very old and unusual boiler. It has some very archaic features, for example it has sliding cast iron balls which can be moved to control one of the valves. I have no knowledge in this area and I've scoured the internet to no avail. There is no maker's plate, no information on it at all. Can anybody tell me anything about it? I thought it was from a steam engine, is that correct? How old is it? Who made it? What was it for? What I might reasonably expect to sell it for? Any and all information would be most gratefully received. Many thanks in advance.

Hattie