That's the one...I'd happily consider fitment of one to my M20 under the heading of 'artistic licence'...It probably happened anyway...By the look of some of the pictures I've seen I think filters were sourced from 4 wheeled vehicles in an act of desperation by REME ...I bought my M20 from an ex North Africa dispatch rider and he said engines only lasted a few weeks maximum without filtration...Ian
The discontinuation of air filter fitment is a puzzle to me. My understanding of all the MEE tests that I've seen suggests no loss of performance or increase in fuel consumption. They were fitted to several small contracts, saw a certain amount of Home Service and then suddenly on the MoS listings for C9681 in early 1937..."Air Cleaners are not now required on the machines". No indication of who decided this, and why. There was obviously an extra cost. Perhaps they decided that it was no longer necessary for Home-based machines.