'HGU' is a 1946 London series. The machine looks to be a Model 18 to trials specification...The forerunner to the 500T but heavy and not particularly agile.
It looks as if the photos were made as publicity for the stand manufacturer. There is a difference between lifting a bicycle into a stand and a heavy motorcycle though...Getting it out again would be interesting too, especially with a kerb behind. I'd like to see a film of people trying to use it !
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