From the historical information I have under the Vintage page, this should have been made by Thibouville. But this clarinet has many of the characteristics I associate with Couesnon. One later characteristic is that it has the adjustment screw on the throat tone Ab key.
This has nickel keys, not chrome plated. I am guessing that this is from the mid-1930s.
In intonation, it is much like the other Martin Frères I have reviewed.