I did as you suggested have a look at the notes to the Fifth Symphony - incidentally they contain an excellent photo-graph of the composer by Mr. Spencer-Bentley, the best I have seen. Your response here, together with those very extensive expository notes written by an anonymous author, contain much of interest, and have resolved most of the questions that occupied my mind.
You're welcome. The unhyphenated photograph by the of necessity hyphenated Mr Spencer Bentley is one of a series of the composer that the photographer took when the composer was almost 96 and, as far as I know, these are the last ones ever taken of him.
One observation caught my eye: Sorabji "loathed meanness and lack of generosity" when it came to composition. It leads me to wonder what Sorabji thought - if anything - about the symphonies of Brahms, in which so much interrelated material is compressed into just a few minutes per movement? (This contrasts does it not with so many - indeed most - more recent modernistical symphonies which are the same length as Brahms's but not nearly so "meaty"
Sorabji was no great admirer of Brahms, though almost certainly more as a consequence of personal temperamental antipathy than of disrespect; he did, however, think highly of the Fourth Symphony, as well he might.
And since you mention them I have looked at the score of Sorabji's Fourth Symphony to find the composer's notes. I cannot remember where it came from...
...I was disappointed though because all I found was a foot-note at one point saying "See Critical Notes." But the Critical Notes themselves were nowhere to be seen.
I do not know if you are referring to the ms. or the typeset edition but I believe that you are referring to Sorabji's Fourth Piano Sonata, not his Fourth Piano Symphony. Sadly, Mr Abrahams has not yet gotten around to preparing his critical notes.
It appears on closer inspection to be the "2004 Simon J. Abrahams" edition so perhaps I should now file it away and not look at it again for fifty years.
OK. I have no idea where you would have sourced this, but I certainly hope that you won't file it away for half a century.