No Vokes filter fitted as original equipment on a 1941 M20...The filter was only factory fitted to the last two contracts of the war and the cut off tank to the last 3 contracts...So, one contract without the filter but with the tank and two with the whole set up...I guess these pictures were taken later after modification....The bike in the first photo doesn't appear to have the cut off tank and the mounting straps for the filter aren't visible either...
I'll stick with my pillion seat for now...Ian