Thanks Alistair (and gnu

)
It's a curly one. I'm still not 100% sure, but I think having seen your photo of the photo, that it might be a print on uncoated paper - something like a salted paper print (see here
http://www.loc.gov/rr/print/coll/589_salted.html). That makes me think that it's a home-made photo, done by someone experimenting with old techniques.
I could be completely off the mark with this but that's what the surface appearance suggests to me!
The other option would be a paper with a matting agent (such as fine silica) applied to the surface, but I've only ever seen this type of paper used with fine studio prints, and the surface is much finer with the grains only apparent using magnification, so I don't really think this is the answer.
So, in short, I'm still puzzled

But thank you for letting me indulge my curiosity

And you have had some great restorations done too, on a difficult photo

Cheers
Prue