Lemania 818 Royal Navy vs Lemania 1872 817 South African Airforce

Both issued in 1975, 818 case to the British Navy and the 817 case to the South African Airforce. How did British markings end up on the dial of a South African Military watch dial? New information below in my Lemania SAAF 1872 article.

https://origintime.co.za/south-african-air-force-lemania-1872-all-you-need-to-know/