I'm inclined to believe Jose's article unless Blancpain has some kind of documentation, patent application, or photos we haven't seen yet. Based on the sparse evidence available, the Perezscope conclusions seem sound. Blancpain's management and marketing staff undoubtedly will become aware of this article at some point, and the question is whether they'll respond at all. If Blancpain does reply, I'd love to see whether there's any kind of defense of the 1953 claim and how it's supported.
Best,
Tim