I'm pretty sure that the bike in the first post is an M20. Certainly not an Ariel primary chaincase.
The pre-war shot shows one of the War Office BSA V-Twins, many of which accompanied the BEF to France, never to return.
The machine with the chair is a sidecar wheel drive 633cc Big 4 Norton. Les, have you got confirmation that the sidecars were made by Swallow ? I have heard it mentioned but never seen proof.
The bike with the Thompson mounted is from a series of pictures taken IIRC at Swanage in 1941. A unit of the Grenadier Guards received 1938 Civilian Model 18 Nortons (500cc ohv) More propaganda than anything.
The picture below is the front cover from "Motorcycling" from April 18th 1940 - 67 years ago next week and shows 4th Battalion Royal Northumberland Fusiliers training in France. The censor has obliterated the "TT" of 50th Div.
