I'm going to call this one solved as everything points to you both having reached the correct solution.
I haven't yet found the source where I took the photo from but will add more information when I find it.
Quite where Serge Pozzoli comes into the equation I don't know at the moment.
To quote another well-known source -
The "Coupe de la Liberation" was held on 9th. September 1945 in the Bois de Boulogne.
Amongst the entries was Eugene Martin's blown 1.5 litre Bol d'Or Salmson.
This was a most intriguing single-seater with circular, protruding, grilled radiator and all-wheel independent suspension"