FN chassis camion 8 1937.
Coachwork by Pritchard-Demolin?
My source regarding the chassis and year is the expert on the Belgian motor industry, Jacques Kupélian.
The puzzle vehicle is pictured (same photo) in his latest book on the history of the Belgian automobile where he states that it was mounted on an FN Type 8 lorry chassis c.1937. The coachbuilder was not mentioned, hence my 'wild' guess!