Most likely woodtype with a backwards cut 'M'?

This appears to be William Caslon's Caslon Italian. [Bad link] by Paul+Barnes of Commercial+Type, but that one is not available. See [Bad link] and [Bad link] for available digital interpretations. The latter departs more from the source.

doesn't have that funky M. but otherwise...

http://new.myfonts.com/fonts/nicksfonts/new-boston-wbw/medium/characters...

frode frank seems to have it right, at least in terms of the origin. Do you think this was a wood version or metal? it certainly looks like it was carved.

The M does look weird, but it follows the rest of the design perfectly - the entire contrast is reversed.

Yeah, saw that in Frode's link — interesting.

Yet another candidate in the close-but-not-quite category: OK Corral by Michael Hagemann.