Gus Kuhn had a Norton racing team in the 1970s. Post-1976 they sold BMWs...I wen there into the 1980s to buy 'Gold-Top' gloves . It looks as if they traded until the late 1980s.
Ah, thank you Henk, you have all the answers, and the photos! Looking at the brickwork on the wall to the right of your pic I think the Forum photo may have been taken round there.
I like the Enfield, pre-War s/v with pressed steel girders. Possibly an S or SF (Deluxe 250) from 38-39? It looks like it has a Dunlop rubber saddle as well. Great picture!
REgards, Mark