They are all from the BSA WDM20 DVD, available from the for sale page of the website. There are about 2500 period motorcycle photos a I use for the website and forum and in total some 5000 images including parts list etc.
I am collecting BSA material like brochure and photo's for many years and especially the last years eBay is a good source to find all kinds of collectable items. Especially the war time photos are a great help to have when rebuilding a BSA.