The late Scottish author, known for his Flashman chronicles, launched a scathing tirade on modern society.
He described political correctness as a "plague" with an inherent likeness to tyrannical censorship.
He wrote: "My chief concern is the kind of prejudice rooted in the feat of being thought illiberal. Such attitudes are dangerous and intellectually dishonest.
"But then, political correctness is by definition dishonest and, I believe, the most insidious doctrine to plague the Western world since those abominable soul mates communism and fascism, with which it has more in common that its dupes seem to realise.
"It cannot face truth; it rejects what is, simply because that does not suit what the politically-correct thinking ought to be."
The comments from MacDonald Fraser, formerly deputy editor of the then Glasgow Herald, are reminiscent of Sir Harry Paget Flashman, the cruel, heavy-drinking womaniser at the heart of his famous works.
Flashman is one of the most controversial characters in modern British literature.
Caro Fraser found her father's manuscript, thought to have been written between 1999 and 2005. She said: "I think he wrote it with an eye on posterity."