RAF post BoB

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I think many could foresee the benefits of high Octane fuel, the issue was mainly producing it in thousands of tons. In the early 1930s filling up a squadron of Spitfires (if they existed) would have cost the price of of a Spitfire.

in the mid-late 30s they ran Kestrels on lower grade fuel than 87oct for training in order to save money. They operated at lower power settings. 87 octane was pretty pricy stuff at times

 

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es, it would have taken a lot of foresight to see improved fuels would enable the Merlin to produce similar power to the Vulture by the mid to late war period.

That is true but they had the advantage that they KNEW the Merlin engine itself would operate at 1600-1800hp without breaking due the work done with the "Speed Spitfire" which was not run on normal gas but rather one (or more than one) of Rod Bank's special blends. But being able to run those power levels for 10 hours or more meant that the basic engine had head room. Some other engines, like the Vulture, had mechanical issues or cooling issues (DB 605? or Hercules ) that had to be solved in addition to fuel issues.
In fact all (?) air cooled engines needed major changes to the engine in order to get any advantage from improved fuels (or lots of water injection).