In your opinion, did the writing of the VM start closer to 1412 or closer to 1440?

[Hermes777]

Cryptographic scenarios are much richer from the 1460s onwards, for instance. There are things that look promising, but they are all a bit late. 

I think as my research shows, in the early 15th century there was a rich, dynamic and evolving cipher culture. See the presentations I uploaded.

I will have a look Mark, and a much closer look at your Council of Basel scenario which I find interesting and which I think has merit.