So it arrived in due course, forwarded to me via England, and I'm very glad to add this one to my collection of (very) early free-reed instruments.
Though I was somewhat upset to receive it in an oversized, lightly padded, plastic mailing bag that was totally inadequate for mailing something heavy and fragile, and almost 200 years old (it needed wrapping in layers of bubblewrap, then covering in cardboard, at the very least) - so that there were numerous slivers of broken off veneer floating about, and even some of the spruce carcase of the case (from where a hinge had broken loose), in the bottom of the bag.
And I was right about there being a Keith, Prowse stamp (and also remains of their label) on the instrument. I'll take some photos of my own of it now, and add them to this thread.
Here's a link to the auction:
Vintage accordion, perfect for partsNeedless to say, my eyes were popping out on stalks when I first saw the pictures...