According to 'the history of Aircraft Lubricants' which can be found on google quite easily, page 12 states that Fighter Command converted to 100 octane as standard on all Spitfires and Hurricanes in March 1940. This matches with the editorial of Flight magazine from March 28th 1940 which is entitled 'hundred octane'.
I'm not sure why not all Spits and Hurri's in the Command are thought to have the fuel by some? The only instance I have read of 'lesser' fual being used is in another 1940 article that talks of the Blenheim using 100 octane for take off and switching to 87 for the rest of the flight (not sure about that myself) but as far as the Spit and Hurri go it seems to be 100 octane all the way.
Also, is it too much of a stretch to read 'all applicable squadrons' as meaning 'all Spitfire and Hurricane squadrons in Fighter Command'?
Good stuff Waynos.
Excerpted from Flight, March 28, 1940:
Full pdf of the article for the reading pleasure of the board membership:
Fighter Station with the Spitfires in Scotland
Anyone care to venture a guess as to the squadron? I'm thinking either 602 or 603, both based at Drem.
Excerpt from: W.G. Dudek and D. R. Winans, AIAA Paper No. 69-779, Milestones in Aviation Fuels, Esso Research and Engineering Company, New York 1969.