Thank you Don and Monsieur E. For example, here is the Ingenia B-29, with an image clipped from the French eBay listing I found AFTER the bidding was over (Rats!). You can see it here:
https://www.ebay.fr/itm/132656680758
You can see "J des Gachons 1944" to the left and above the image. His usual style of signing. M. E, I think this could mean it was printed during the war, perhaps in Great Britain. He has other designs from 1941 and 1942 indicated in a similar fashion. Or do you think he designed them secretly, and laid them aside until after the war was over? Here is the close up.
By contrast, Shefer usually hid his signature somewhere where it would be visible on the finished model. I attach an example of that with E. A. Schefer's signoff next to the tail wheel on the Farman 224.