I know this because I have guns stocked with it, and have at least four two-piece French Walnut blanks in my inventory. For a guy who acts as if he knows everything about doubles... even though you don't own even one... you sure do spout a lot of incorrect information. 
How do you know the Walnut blanks are French?  Did you fall those trees yourself and cut them into blanks?  

   Are the guns so stocked made in St.Etienne?  Gee, I didn't know you were so diversified and accepting of French products.
I do not want people to think that I'm cruel and unhelpful fella.  Here is what could be considered near mid-grade Walnut grown somewhere in Northern France.....or Southern England  

 .....The gun is from the shop of well-respected gunsmith in Paris, France,....  
From shop of Charles Francois Galand.......