[pierrem15]

The American definition of an inch and the British both used the meter as the ultimate reference, but differed by a few thousandths.

However, when they sat down together in 1941 to examine possible parts discrepancies between the allies arising from this difference, they didn't find any: the Swedish tool maker who manufactured the world's standard measuring instruments had emigrated to America in the teens and had decided to just use the American definition. As the Brits bought his tools, they had switched over to the American inch without knowing it.

[Mogger]

The American definition of an inch and the British

It was the development of machines and measurement equipment to make interchangeable parts.

[marktwain]

the Swedish tool maker who manufactured the world's standard measuring instruments had emigrated to America in the teens and had decided to just use the American definition.

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L The video I watched showed the Swedish toolmaker chose a number in between the the British and American definitions, because he did not want to have two assembly lines for his precise tools for rifle manufacture. It was Carl Edvard Johansson. He developed the system in Sweden. Later, Ford bought the company outright because the Swedish company was going bankrupt.

https://www.youtube.com/watch?v=w_yurKxgtLs