My 1949 M33 sort of started life as an M20 and is fitted with girder forks. The previous owner stated that it came from Pride and Clarks so equipped. That I know means nothing regards Pride and Clarks. I have seen a few pictures of 1949 M33s fitted with girders.
This is my 1948 BSA M21 YM frame number despatched 22nd June 1948 matching numbers, so I assume one of the last of the Girder/rigid M series BSA,s. 1949 M series should have a ZM frame number and as far as I know had tele forks, I had a 1950 ZM with tele,s never seen a ZM front frame with the long front down tube for girders though ? Dave