Very interesting and unique seat stay caps. Unfortunately I have not come across an exact match, so I can't say (yet) what this frame might be.


At first they reminded me a bit of the concave stay caps you'll find on Robert Ducheron and some Liberia frames, although obviously quite different:


Ducheron:






Liberia:






A marque that did something similar to this mystery frame is Luders (out of Berlin):




Again, different, plus I have never seen a Luders with French Reynolds decals let alone French threading.

There was also a very old French frame that was posted on tontonvelo.com years ago, but was unfortunately never identified. It's kind of a cool looking twin tube frame:





Finally, there's a similar treatment on a contemporary frame by a Belgian builder Nicolas Noblet (too young to be linked to the mystery frame):



The rest of the set of the bike above can be found here.


Sorry I couldn't be of more help. I'll keep an eye out and hopefully we'll have a resolution one day.