The world is full of 35mm format cameras, both film and digital, with interchangeable lenses, but few people know that this practice commenced in Britain in the late 1920s before Leitz started its own range of interchangeable lens cameras with the I Model C, which was introduced in 1930. This involved conversions to the hitherto single lens Leica I Model A, introduced in 1925, to allow the fitting of some British made lenses, such as those made by Ross and Dallmeyer, both of whom had been optical giants in the British market since the mid 19th Century. German made Meyer lenses were also fitted to Leicas in London by A.O. Roth who was an importer for the brand. Some of the innovations created in Briatin fed into the later models introduced by Leica and others and, in one case, the feature still exists on all interchangeable lens cameras to this day.
My Video on YouTube was made for the Photographic Collectors Club of Great Britain (PCCGB) and also gives the 'before' and 'after' sitaution as regards changing lenses without the use of a lens board.
https://www.youtube.com/watch?v=DOqNGCAIOsU&t=71s
Some photos (courtesy of Wetzlar Camera Auctions) from my video featuring a Dallmeyer Dallon Tele- Anastigmatic 4 inch lens on a Leica I Model A from 1929 are below. This conversion was done by Sinclair who had a shop at 9 &10 Charing Cross which became 3 Whitehall around 1930. The shop did not move, but the address changed
