I was chatting with a moderator of another helmet forum and got this answer...
Hi Mats,
Nice story, but in my opinion this is a scam attempt. Namely, it is not true that this type of helmet was in production during the First World War. They are typical from the 30s and were very much a private purchase among officers.
The silver colored manufacturer's logo is typical 30's style.
These cork helmets were fragile, and most examples that have survived to this day have peeling paint. Namely, I think it is quite obvious that the blue color is new.
Another detail is the nuts that attach the stars. If this was a special order they would not have used this system to attach these and cover with fabric as the artillery emblem. Last but foremost problem is that this helmet has an artillery emblem. But General Maitrot was an infantryman throughout his career and would never order a custom-made helmet with an artillery emblem...
So i say buyers beware...