[Juha]

Hello Graham
even without new engines the new cockpit and new outer wings would have bought some drag reductions and so performance increase and would have given better view and more room to the crew.

I understand well the difficulties of wartime production planning, British had their own mistakes and difficulties, which are sometimes forgotten when discussion centered on what RLM did and didn't and IMHO a small improvements, if possible without too big production losses, is better than no improvement at all while waiting a “super-plane” which never arrived. At least in Spitfire development British were wise enough to put interim designs, like Mk V, IX and XIV, fast in production when situation demanded without waiting that the proper designs, like Mk VIII and 21, were finished.

Juha