Quote Originally Posted by Steven Tribe View Post
For me, the most significant link to Vallantin is what he engraved on his lenses - this is very similar to that found on Colas lenses.

So I think the likely scenario is :

Colas discovered a UK market for sliding box cameras around 1856. He had the cameras made and had an agreement with the newly independent maker Vallantin (ex-lerebours) to supply lenses to be engraved in London. The "light" engraving is very typical of UK brass engravers. It is in French and says Paris - France was still regarded as the home of Photography.
This is such helpful information. I hadn't considered disassembling the lens before so I did and I found that you hit the nail on the head, Steven. The front element is marked Vallantin. Here's a photo.

I also appreciate anachromatic's clarification the Élève is better translated as disciple.

Scott