Somewhere I've got some photos I took some years of one of these mounts on a rifle belonging to Adrian Dagger. I did upload them to a hosting site, which folded some years ago taking them with it. Must find the prints.
This, on the other hand, is entirely made up, quite recently, by a talented retired engineering worker who brought it up yesterday. The Aldis sights were available as parts from the trade into at least the 1950s.