PoyFR is a good friend and knows his stuff.
I believe there were two case-makers or more exactly case making coordinators. The first is Montres Valgine in Switzerland and the second is CORO from Italy. AFAIK, Valgine made the 201/A up to the 207/A and CORO, the 209, 210, 218 and some 400 or so OP6500 already under Vendome. I don't think PoyFR will have a different opinion
If somebody can shed another light, I will be the first to be happy about it.
Cheers and best from the holyland,