I started replying to this one, then hit a snag. How do you get the organisational setup that can do this? Throw enough designs at the wall to get a few good ones that stick- explore all the possibilities on the drawing board, then pick the best for production?
Now, ships you can build like this, shipbuilding firms can produce to common plans and there was only to all intents and purposes one warship design firm- the Admiralty- in the country;
but how do you make that happen for aeronautics, especially after a setup like that turned out disaster after disaster in the first world war, and the RFC was only saved by the types the RNAS had commissioned from a multiplicity of private contractors? There is timeline fodder here, I reckon.
You have to decouple aircraft production and aircraft design, which means firms don't have their own warplane design teams- and there isn't enough civil aviation trade to support them, so- you'd have to destroy the organisational basis of the trade, and how to teach it in those circumstances? University departments of aeronautics perhaps? Hm.
(Almost anything has to be better than bloody BAE, though.)
So these departments produce designs to Air Ministry order, assess them, the ministry pick the best- and administrative arteriosclerosis is going to be a big, big problem here- and order them from likely looking aircraft firms?
In that unlikely event, and the even more unlikely event of their actually getting it right, which those three seem to be, you basically have single engined jobs, twin engined jobs and four engined jobs.
Single engine, Spitfire as jabo, bit fragile but fast and difficult to intercept, but Army Cooperation (artillery observation) is right out- and training? Dear god. Desperately need a simpler basic trainer.
And there are a lot of single engined carrier aircraft, and oops. The idea of a torpedo bomber Spitfire just... no. Endurance is going to be problematical, to say the least, and there would need to be some fairly radical changes made.
Twin engined jobs, getting the Mossie to do every warlike job that might be asked of a twin engined aircraft isn't really that much of a stretch at all- I take it we are still allowed variants? The low speed, high endurance, stooging work like anti- U-boat patrol is the only thing I can't readily come up with an existing Mosquito variant for, actually.
It's the unwarlike jobs, the squadron hacks and personnel transports and advanced trainers and the like, that the Mosquito is too much the high performance thoroughbred to stoop to.
Four engined- on a pure Lancaster diet you may need to muzzle Pierse, Portal and Harris at this point, because they will demand them all, and there are other jobs that need doing- MPA for instance, although well, Shackleton, and transport/glider tug, and it would have to do all the utility/hack work accomplished by humble things like the Bristol Bombay and the Avro Anson and other twins that the Mosquito is too lean to fill the role of. Might get a Griffon engined version, though.
You'd have an awful lot of thoroughbreds pulling milk floats, but on the whole yes, probably better off, especially the light/medium bomber units.