My mate had a square four in 1968, with an old sidecar. I think it previously belonged to his dad. Spent more time working on it that riding it (as you did in those days ). Eventually he sold it and bought , i think a Matchless 500 or 650 . There was a chap down the street had a 50s Ariel , same colour as in your photos , with a Canterbury? sidecar. We used to call him "the old guy". He was actually only 37.
Quite funny really to think that when my mates motorcycles broke down he used to call me and ask for a lift to Bristol Temple Meads station. .........
on the back of my "modded up" Lambretta. Happy days!