I share your passion.
There is a very well illustrated article on Parker Hale sighted Webleys in Issue 3 of on line magazine Airgun Collector. The present edition of Airgun Hobbyist, which is published in the States also includes a couple of aperture sighted BSA Airsporter/Clubs.
As my eyes grow older and weaker, I find aperture sights not just a desirable accessory but essential for shooting too! There were numerous aperture sights intended for pre war BSA air rifles and a fine collection can be assembled consisting of such rifles.
Kind regards,
John