A friend sent me this picture which is captioned "August 16th 1940 Bootle, Liverpool. South Wales Borderers exercising" I've ID'd the ones I can see as Triumph Twins.( 500cc Speedtwins ?) Apart from the second one up on the right, which also appears to be a Twin or Twin port. Ron
It's IWM H 3096. Presumably a well-known photo as the old RvM Chilwell list has C4328988 listed as a T100 and C4328979 as a Rudge. It certainly looks like it, with the stand handle visible.