We used to live in Wickham, WA in 73-76. My late husband restored a G14, looked fairly similar but it had a larger V engine, now back in the UK in my brothers spare bedroom! It was what they called a "Colonial model" - with a few differences to the usual UK models. One of the differences was a gear change lever on the tank, rather than foot pedal.
I'm sure if you go to Google UK and then go to the BSA Owners Club you should find the answer. My brother won't be back home for a couple of months, but I'll ask him when I see him next.