and no need for further doubt,even the primary site says BSA
Guy Scheers, from Belgium, is the proud owner of this BSA M20. Here's another view, and one before restoration.
He writes, "I found the old rusty bike in the garage of my grandmother when my grandfather past away. Before he died, I was not allowed to get in there, because his son (My uncle) died in an accident with the same type of bike.
The BSA was collecting dust for over 27 years! It was a pleasure to restore the bike. Fortunately I got some help from my brother, who you can see working on the picture.
Riding the bike is like... heaven.
Special thanks to my grandmother, my lovely girlfriend (Inge), my sister (Cindy) and my brother (Rudy).
http://www.strappe.com/britbike_pics.html