You are just miss understanding the point I was making which was mainly about available thrust. The Merlin eventually produced 2,000 BHP, Mitchell would have produced a much different design based on a 2000BHP Merlin and Variable pitch props. It is common here to quote the difference between a Spitfire MkIX and a P-51B/C or D which had the same Merlin engine, but it was a much different Merlin to that of 1936. A P-51 with a Merlin MkI, II or III and a wooden two blade prop would struggle to get off the ground at all, but it wasn't designed to, it was designed a few years later when planes all had constant speed props and 1100-1200BHP. I am not moving goal posts, I am saying how much goal posts moved between 1934 and 1940. This is borne out in later enquiries by the USA into UK aircraft engineering standards, basically why UK aircraft were lighter, they were lighter because they had to be, so the engineering standards sailed "closer to the wind" to the edge of what was safe and reasonable.We're all entitled to opinions. However - denying what is a reasonable proof and moving goal posts to prove an opinion? C'mon.