Other than the many provided combat reports showing it's use and complete absense of any showing the use of 87 octane....no I guess there isn't the elusive document that says it verbatim.

I would suggest that this is a strong indication that "specifications" followed singnificantly behind widespread adoption in combat during this period.

It does not work that way.

So is it illegal to specify an unspecified element in a combat report?

Except for the stocks, combat reports, Oil Position meeting notes, various pilot's memoirs, squadron log books etc etc.

The case is stronger than the one you're putting which seems to be "because I say so". Time and time again you've made some statement which has turned out to be completely wrong, completely.

Then you come go quiet for a day and re-appear with a slightly differentley worded version of the same thing.

There were literally 100's of modifications applied to Mk1 Spitfires during the production run yet there aren't 100's of versions of pilot's notes.

There is only a small pool of squadrons on the combat reports. Only a fraction list +12lbs and instead use the phrase "pulling the plug" as proof of 100 Octane use.

While "pulling the plug" was used to express 100 Octane, it really just means they gave it all the engine has got.

Got proof?

I am speechles. :eek:

Good heavens! You're a cultural guru too Crump.:-)

Unfortunately the study of history works that way.
If you have positive evidence for the use of X, then official documentation which endorses X need not over ride the positive evidence, if found to be from a later date.

Below is what I would refer to as "positive evidence" of the use of 100 Octane prior to the "specification date". In fact the below gives us a strong indication, (and I would say proof in the case of the combat reports and photos referencing +12 and/or 100 octane directly) that, in fact 100 was being used prior to the specification. Not only that, but that 100 octane was used on a wide-scale, at least as far as the spitfire was concerned.

I have made a list, of all the references I can find to the use of 100 in COMBAT from freburary 1940 to September 1940, by squadron.

The list is not exhasutive and simply indicates the first date at which I can find various references. I have grouped these by the type of reference, from explicit mentions of particular boost or octanes (in photos or reports), down to mentions of "gate" or "emergency power/ boost cut out" which are almost as persuasive as direct references to the use of the 100 fuels. I am going to continue researching this to see if I can find further evidence/ data that indicates at a minimum the "in-use-by" date for the various squadrons.

Here is the results:

referecnes to +12 Lb and/or 100 octance
602 squadron: February 1940 - photo of squadron aircraft in in pre-BoB paint with 100 written on the fuseage + squad operations book entry on 16/2
54 Squadron: May 1940 - combat report from colin gray on 24/5 & AL Deere Combat report 26/5
19 Squadron: May 1950 - combat report from flt Lt Lane 26/5
610 Squadron: July 1940 - photo of 100 fuel bowser refuelling A/C
41 Squadron: June 1940 - combat report Flt Lt Webster 19/6
64 Squadron: August 1940 - combat report from P/O Donahue
72 Squadron: September 1940 - Combat report from P/O Elliot 9/9

References to Boost Cut out/ emergency boost/ "gate"
74 Squadron: May 1940 - combat report from P/O Freeborn 24/5
611 squadron: June 1940 - combat report from P/O Brown 2/6
610 Squadron: June 1940 - combat report order to "gate" 12/6
616 Squadron: August 1940 - combat report from F/O Dundas 15/8
603 SQuadron: August 1940 - combat report from P/O Morton 28/6
152 Squadron: September 1940 - combat report from P/O Hall on 4/9
66 Squadron: September 1940 - combat report from F/O Oxsrping 6/9
234 Squadron: August OR September 1940 - recollections from P/O Doe
92 Squadron: September 1940 - recollections from Goeffrey Wellum

reference to high boost (+10 LB)
602 Squadron: August 1940 - combat report from Flt Lt Boyd 18/6

I am not sure how many of the above are spitfire squadrons, but there are 16 Squadrons listed there (610 is listed twice, as I located references in two categories). I understand there are only 19 Spitfire squadrons which have battle honours for the BoB.

Now, to wider matters, it seems to me that there are two separate assumptions being made in this discussion, these boil down to:
1. That twe must assume the use of 87 octane UNTIL we have positive evidence of the use of 100
2. That we must assume the use of 100 UNLESS we have evidence of 87.

I would say that Crumpp, falls into category 1. I agree with him/her on this account. However, I think we have ample evidence to suggest that many units were in fact using 100 on a staggered basis from February 1940.