Hi, I have an alto Besson London s/n 41193. It has many features typical for hi-end horns of pre WWII era such as rolled tone holes, all mother of pearl keys, microtuner neck, trill D# and G# keys and unusual roller on Bb valve. I think it's a stencil of good manufacturer and I wonder wich. I post a few photos. Please if you have any idea who can made this sax tell me.