More of the decal on the seat-tube.
On one side it says "World Champion 1937"*, on the other side it says "9 Times French Champion". I have not yet found anything more about this; don't know if it concerns Road, Track, Cyclo-cross, Male, Female, Junior, Amateur or Professional.
The signature on the part at the top I have found out - Gérard Leroy - eventual owner (the son?) after the founder. Here he is behind the counter.
Frames hanging up, tyres and tubs hanging up, and bike parts in glass cabinets
I'm still struggling to find out what the signature on the bottom part says.
* I'm fairly sure it is 1937, but it could be 1931 - the French typically put a strike through on the sevens at least in written form.
EDIT: A correction after checking the signature much closely.