[Graham Boak]

There were not "some" Spitfires modified to fly across the Atlantic. There was one - it involved removing all the armament (which really would have been particularly useful for a long range fighter), converting the wing to an unsealed fuel tank and the fitting of a fuselage tank that rendered the aircraft only capable of very limited manoeuvres. The result was a useless freak.

That the Mustang was built with a large internal fuel capacity to RAF requirements might, I'd have thought, make it rather difficult to argue that the RAF was totally opposed to long range fighters.

There were three developments that lead to the successful development of the long range escort fighter.

The first is the availability of a fighter with a high fuel fraction. Given that the RAF's prime responsibility was the defence of the United Kingdom with short warning times of attack, this led prewar to the development of aircraft where light weight required a low fuel fraction. You might find it interesting to compare prewar use of the high fuel fraction fighter such as the Bulldog as opposed to the low FF fighter such as the Fury. This approach is not something that could be rapidly turned around: it takes a number of years from the issue of a specification to the appearance of the resulting type in significant squadron numbers. The Tempest is perhaps an example, which reached RAF service not far behind the Merlin Mustang.

The second was the widespread adoption of drop tanks, something that did not begin until late in 1940 and was fairly rapidly developed for the Spitfire and other RAF fighters. However, there is a limit to the value of drop tanks for a fighter with low internal fuel loads - they are not carried in combat and there is no point in flying out further than you can return after combat.

The third was the addition of extra fuel tanks behind the pilot on the P-47 and P-51. Until then the operating radius of the P-47 was little further than that of the Spitfire. These tanks required a sizable amount of space and a sufficient cg range: even then the fuel in these tanks had to be used up immediately after takeoff and the aircraft had to be very carefully handled, with a high workload on the pilot. The Spitfire had a smaller fuselage, with less space behind and a more limited cg range. A rear fuselage tank was developed, but was not acceptable for service until the heavier Griffon variants, which being thirstier than the Merlin added little to the practical range.

The combination of these factors, not all of which could be successfully predicted in 1941, are what lay behind the eventual success of the long range fighter in late 1943/early 1944. The early RAF interest in the Merlin Mustang, and the development of fighters such as the Tempest and Hornet, give the lie to ill-informed claims that the RAF were not interested in long range fighters. They were when they could get them.

It is worth remembering that the RAF was not monolithic: in addition to the bomber barons there were fighter-biased marshals, Tedder with his development of successful ground-air co-operation that showed the way for all other nations, and those pressing for increased maritime emphasis. All were working towards eventual victory, all were developing their own particular areas. That at some stages a priority was given to the bomber offensive does not rule out all development elsewhere.

Repeating that the divebomber is the best solution for air-to-ground in all circumstances does not make it true.