You see, back in 1954 Wirgin introduced their Edixa Reflex:
It had lever wind on the right side. Film reminder dial around the rewind. The typical bottom location of the film rewind button, and the centered tripod socket... The prism was interchangeable though and Wirgin introduced automatic aperture operation in 1956... it took a while for Pentax to adopt. Of course the Pentax had an instant return mirror and the Edixa didn't.
The Edixa is oddly forgotten today. Kind of like how people forget Topcon's contributions to the development of the SLR.
Do you have another reference for the 1954 Wirgin Edixa Reflex? This site states a different year -> Edixa Reflex (1957). Perhaps a different model?
Of course arguably the single biggest advancement that opened the SLR floodgate was Asahi's instant - and automatic, mirror return.