Think I've got it...
The scooter is a Mors Speed, the brain behind is Pierre Brissonnet !
I guess there was a connection with Paul Vallée, maybe Mr. Brissonnet has worked on both projects, the P.B. and the Chanteclerc !
Mors scooters were produced in a factory of Sens. And yes, it was the same Mors famous for his luxury cars until 1925...
Much, much later, the Mors brand was even used as "MTM" (Mors Transmissions Mécaniques) for a transaxle and a rack and pinion steering used on many voiturettes in the eighties, previously known as "Renondin-Losson"...