Frame number WM20.45636 (census number C4555145) was despatched from the factory on 19/09/1941.
Frame number WM20.45319 (census number C4554828) is the closest number the I can find in my pictures. It was despatched during the same week, on 13/09/1941.
I've just noticed the bike in Jans photo has a Vokes filter....Not original fitment so it must be a retro fit...I wonder when the photo was taken?....Ian