In my post #47, I claimed that I had checked every manufacturer of the period, and cross-referenced to Georgano, and could find nothing. In fact I had discounted Mochet, simply because I believed they had only built microcars. Sheer laziness and an unjustified belief in my own knowledge, and I paid the price! It's there in Georgano, even if it's just one line. And when I checked entry lists for Montlhery, I had only gone as far as 1954.
Well done PJ.
That was a great puzzle.
(PS the car is missing from the results/entry list for that race. That certain site is not infallible.)