Just after I posted 'Chambas' I learned a little more information - enough that a second post is necessary.
Even though the car is more regularly called the T26 GS 'Chambas', the name comes from the highest-profile owner of the car rather than the actual coachbuilder. Andre Chambas was a rather successful French industrialist with a close association with the factory Talbot-Lago team. He bought the car with racing in mind in particular, and had the body built by Contamin.
Whether this particular car is a 1948 or 1949 model is debatable, but it first appeared for competition in the 1949 LeMans. By 1952 the same car had been rebodied into a Barchetta and was running with a supercharger. The original body was reinstalled sometime in the late 1950's when its racing days had passed.