Hello, John..don't lose any sleep over correcting anything I might have submitted, as no doubt there are several correct answers to your question.
My mention of DILECTA as being a supplier is based on having seen an actual bike, while my suggestion about Oscar Egg is simply base on reading M Arbes wonderful site.
Jock Wadley was a very well-informed person indeed, and it would not surprise me at all if, as he said, ALCYON, supplied some of the frames and bikes.
I read somewhere, a Dutch site I think, that ALCYON rates as the world's most successful cycle racing team, based on a points basis...way ahead of teams such as Bianchi, Peugeot etc. I think that ALCYON riders have also won the Tour de France more times than any other team.
ALCYON were based in the northern Paris suburb of Courbevoie and had two large showrooms in central Paris..so it is likely that the Paris-based publishers of L'Auto would be well acquainted with the firm.
At the height of their fame in the 30s ALCYON frames were called 'autogenes' indicating that they were built by fusion welding. I have a 1936 Tour de France model complete with Super Champion Osgear which has the lugless frame with a very elegant steel plate internal fork crown. So..if we can turn up any photos of T-d-F riders using lugless frames yellow frames with L'Auto transfers and sporting aero crowns we will probably be able to confirm Jock's statement.
Norris Lockley
Settle UK