now Gavin's article is a scientific article published in a well-established scientific journal and so it has notes, so you have the notes and so you can check from where the info has come, so you can check it and dig deeper if you want e.g. Search results: CAB 77/3 | The National Archives for CAB 77/3.
Scientific papers are not God's words but you can check the claims and use notes for deeper study if you want.
I did my homework and read Gavin's article (as well as 10+ more articles). Gavin's is a very solid piece of research and I see little to nothing to criticize. Footnotes also give plenty of ideas where to dig further.
(The only thing I noticed is the author ignores CAB 50 Oil Board series - which is full of documents on high-octane aviation gasoline - but rather uses isolated items found under AIR 2. )
However, this article is not interested in when the 100-octane was rolled out to fighter squadrons of the RAF. This was the question starting this thread.
But since Gavin also points that the benefits from this improved fuel were "marginal, and perhaps even insignificant", the matter is moot. I just wonder why heated discussions started over that point 10 years ago.