Here's what I have, from Glider.

Part II.

With regard to "units concerned" as per above. Having looked at the WWII classified secret file with the title "AVIATION FUEL (100 OCTANE) SUPPLIES", it can be seen that when read in context, the file is refering to the enclosure containing a letter dated 7th December 1939, ref: FC/S.15447/76/EQ.2, under cover of Air Vice-Marshal, Air Officer i/c Administration, Fighter Command, Royal Air Force.

This letter details the operational stations at which the 100 Octane fuel will be required "in the first instance". The letter also states that "all non-operational stations in the Fighter Command will also have to hold certain quantities of this fuel for visiting aircraft". The letter goes on to list the non-operational stations and stations which do not have Hurricane or Spitfire aircraft at the moment, that will need the fuel. The letter also mentions the need for "disposal instructions for varying quantities of D.T.D224 and other grades of petrol that will not be required in such large quantities on the introduction of 100 Octane fuel".

A letter later on in the file, dated 12th December 1939, can be seen to be responding to the AVM's letter, ref: F.C. 15447/76/E.Q.2, on behalf of the Air Officer Commanding-in-Chief, HQ Fighter Command. This letter says "I am directed to confirm that 100 Octane fuel is approved for use in Hurricane, Spitfire and Defiant aircraft, and state that issue will be made as soon as the fuel is available in bulk at the distribution depots serving the Fighter Satations concerned" (the ones listed in the AVM's letter dated 7th December 1939). This letter also says that "from an operational point of view it is essential that supplies in bulk at the distribution depots should be available before general use commences and that it is not possible to state a day on which 100 Octane fuel will come into use on all the approved stations" (the ones listed in the AVM's letter dated 7th December 1939). The letter goes on to say "the date on which the fuel may be brought into use depends upon the rapidity with which (a) supplies in bulk can be put down at distribution points, and (b) bulk storage could be made available at the relevant stations". The letter also says that "the Petroleum Board have been instructed that storage in bulk at certain distribution points is to be arranged with the least possible delay and tanks at these ponts are being "run down" to provide the necessary accomodatoin".

I think it is reasonable to consider that the term "with the least possible delay" means that 100 Octane fuel was was used in all Fighter Command approved aircraft, which has been given as Hurricane, Spitfire and Defiant, very soon after the letter dated 12 December 1939 from the office of Air Officer Commanding-in-Chief, HQ Fighter Command, RAF.

Talisman

For the record 'those crops' as Kurfurst so describes the paper are the only part of those meetings that dealt with the purchase, storage and distribution of 100 Octane fuel and Kurfurst is aware of this. It isn't a case of being unwilling, its a case of there is nothing more of relavence.

He expesses doubt but has had ample time to obtain copies himself to prove it one way or the other.

I am pleased that he has finally posted the papers available which show the trail in context rather that emphasising one paper.

Like I said, he is not very willing to show anything but crops.

He DOES insist every time to see the full papers I use to post though, and as I recall he seen them in full every time.

Indeed.

"At the last meeting A.M.S.O. referred to a proposal that certain Fighter and Blenheim Squadrons should begin the use of 100 octane fuel.."

Quite clear-cut isn't it.

Here's my take on this "units concerned" business, working from most recent to oldest:

By May 18th, these "units concerned" has been stocked with the necessary 100 octane

Prior to May 18th. There are two separate lines of discussion.
One relates to Bomber command and the stocking/ holding of two fuel types a Blenheim statinos, mainly stations Wyton, Watton, Waattsiham and West Raynham.

Fighter command, on the other hand was also subject to the same "proposal" that "certain units" should "begin to use 100 octane". There was some discussion about whether or not the existing spitfires and hurricanes could actually convert to the 100 fuel without substantial modifications. However, this concern was proved unfounded. They could use the 100 fuel.

So who are these "certain units"?
Well, as Talisman identifies in his post above, these "certain units" are the "squadrons armed with fighters and Blenheims" as specified by Assistant Chief of the Air Staff - who sits ABOVE both fighter and bomber command, which is why, form the overall RAF perspective this refers to "certain units", and not ALL units.

I think it's entirely fair to suggest, that from the perspective of fighter command, this referred to ALL fighter units.

I am in agreement with Talisman that by May 18th, all of these "units concerned" were using 100 Octane. And that their Spitfires and Hurricanes could use the fuel WITHOUT considerable modification, as per the statement of Mr Tweedie, at the May 1940 meeting.

There is a sting in the tail though, while the Spits/Hurris could use the 100, they would not get the performance benefit until the modifications had occurred to each individual aircraft.

And why do you think it does not refer to the original 16 squadrons?

Name these 16 original squadrons.

Which "original 16"?
Who identifies these "original 16". I've not seen this bit yet (it might be too far back in the thread).. I'd happily accept a fresh link, if you'd oblige.

Assuming it were only these 16 (none of which I can find), if say, one of these 16 (as yet unidentified) squadrons was based at at a station with other units not in the 16, would that station have had both fuels?

Do you agree that the "certain squadrons" are those squadrons which are referred to in the request by the ACAS?

Lets' start with establishments common ground, and work from there.