At the risk of repeating myself, since I haven't contributed to this thread-
I got my first experience with Whitworth when I bought a Triumph Daytona 500 in 1970. The bike had problems and warranty fixed it the first time, but 3 months later when I had moved to near New Orleans, the dealer there didn't want to honor a warranty on a bike not bought from him!
I bought a service manual and took the top end down myself. I soon found the fasteners weren't exactly compatible with the wrenches I had, so I bought Whitworth.
Later I became a motorcycle mechanic and did a lot of work on Triumph and BSA bikes.
Even later, I owned an MGA and needed them again. Those wrenches are still in my tool box somewhere, along with tins of Whitworth fasteners.