I think you've probably solved this one Djetset.
One point more for you.
I have it as a Gillet being driven by Vroonen at the Bol d'Or 1932.
I have since found in a history of Belgian motorcycles that Vroonen was responsible for the construction of cyclecars (number built unknown) using Gillet engines and mechanicals.
No further information on engine size or other details at the moment.
Vroonen had competed with Gillet-Herstal motorcycles and sidecars extensively in the late 1920s.
S.A. des Ateliers Gillet were established in 1919 at rue Hayeneux, Herstal.
They finally ceased production in 1958.
I believe the company used the title Gillet-Herstal to distinguish it from the French Gillet concern.