Oh, they lie... or at least they did.
thought I've told this story. For a short time I was assigned Ford Austalia project. One of the things I had to do was make the brackets up to fit their car, based on their drawings. They had a bolt identified in what looked like mm, but wasn't a standard metric bolt. Because of the time difference it took a couple days to get the answer back that it was a Unified thread bolt but they put a close metric dimension on the drawing to disguise the fact. :rolleyes: :BangHead: I think it was after that I was talking with a daftsman from Jaguar who had amusing stories about Witworth still popping up along with Unified and Metric when he had worked for Leyland or Rover, cant recall which now.