Manufacturer and year will do for one point.
Experts?
Well, no expert was interested. So your turn pro's. This won't take long, I guess.
Labourdette body on an Amilcar C4?
I know the name of the company who build it, the name of the owner of the company and who bought the car. Don't know the name of the coachbuilder. And it's not an Amilcar.
French at least?
Yes, it's French.
An Able, manufactured in Avignon, France, from about 1923?
Yes, an Able. The company was owned by Monsieur Paul Toulouse. It was located in Avignon. The car was bought by Monsieur Felix Gautier who lived just 200 meters from the factory.