buffnut453
Captain
As I understand the two companies simply took different ways of manufacturing an engine to the required tolerances.
In the UK, with cheaper labour and (generally) shorter production volumes they'd produce components to looser tolerances, then after manufacture get these groups into matching assemblies with the required tolerance.
In the US, with more expensive labour, larger production runs and presumably a more highly developed capital raising system they'd spend more on production machinery that produced tighter tolerances in the first place, without requiring the manual sorting and matching.
Both were valid for their particular circumstances.
Please explain how your concept of "shorter production runs" tallies with the plain fact that British Merlin production outstripped American production by a considerable margin.
That British production included setting up brand new factories in areas where there wasn't a skilled workforce pool. That's not something you can do using the approach of hand-fettling each part.