Interesting, given that I've read that Americans were far better at mass production than the Germans. My impression is that Germans engineered their hardware better than Americans but they were not as good at mass producing it fast.
So if I understand correctly, the British was exceptionally slow at manufacturing compared to the Americans then.
I read years ago that the Spitfire required twice as many labor hours to produce than the Me-109. The Germans were pretty good at simplifying the design so it could be mass-produced.
It depends upon your definition of "slow". At mass production, maybe. But maybe faster at changing and iterating on designs due to being more flexible and adaptable.
So if I understand correctly, the British was exceptionally slow at manufacturing compared to the Americans then.