An interesting last few posts. It reminded me of something I read recently in Sir Stanley Hooker's book 'Not Much of An Engineer'. In it he talks about when RR wanted to get Ford's in Manchester to produce the Merlin.
Ford went down to Derby to have a look at the blueprints and announced they couldn't manufacture engine to these drawings. RR assumed they meant that the tolerances were too fine, but Ford said it was quite the reverse, they were too course! Ford explained that they produced many thousands of car engines where all the parts had to be interchangeable between engines and RR standards were not good enough to achieve this interchangeability.
In the end Ford's took away copies of the blueprints and re-drew them to their standards.