They are lovely, but I agree with Rik, more likely just postwar because of the number of colours, but as they appear to be printed in house by BSA maybe I'm wrong?
I found documents from the Irish army motorcycle training manual with hand drawn versions of these
It’s clear they had based these drawings on the bsa issued diagrams seen here
They were dated as Training instruction No 30 in 1949 but a note on the cover noted that this edition rendered Ti 30 from 1943 obsolete
