These are Spanish Civil War photos from the archives of the Communist Party. It's fairly well known that the Norton Model 18s and the Enfield Model Js were supplied via the French importers (The Psalty brothers - Pierre for the REs and Lucien for the Nortons)
Presumably sanctions or the general situation prevented deliveries through normal channels. I'm not sure how the BSAs arrived there though.
My Friend in Spain, who from time to time has m22 spares sent me those photos.........He said that the spanish republican army had a penchant for buying the best sports models...........they also bought velocette, sarolea, gillet, herstal, harley, and triumphs as well
