The Nobel laureate Sir William Golding, whose novel Lord of the Flies turned notions of childhood innocence on their head, admitted in private papers that he had tried to rape a 15-year-old girl during his teenage years, it emerged today.

Golding's papers also described how he had experimented, while a teacher at a public school, with setting boys against one another in the manner of Lord of the Flies, which tells the story of young air crash survivors on a desert island during a nuclear war.

The revelations will appear in a forthcoming biography of the writer, who died in 1993 at the age of 81.

John Carey, the emeritus professor of English literature at Oxford university, was given access to a personal journal kept by Golding – who carefully guarded personal information during his life – for 20 years.

The book also draws on an unpublished memoir written by Golding for his wife, Ann, who died in 1995 and is buried beside him at Salisbury, Wiltshire.

The couple were married for 54 years, and Golding felt the honesty of his account would explain what he described as the "monstrous" side of his character.

The memoir, entitled Men and Women Now, makes no attempt to hide the author's regular dependence on drink to fight his demons.

He was also explicit about problems with his parents, and suggested that the girl he tried to rape had later plotted to get his father, a grammar school teacher in Marlborough, to watch them having sex in a field through binoculars.

Carey outlined his findings in the Sunday Times, for which he is the chief reviewer, in advance of extracts from the biography which will be published next week.

The attempted rape involved a Marlborough girl, named Dora, who had taken piano lessons with Golding. It happened when he was 18 and on holiday during his first year at Oxford.

Carey quotes the memoir as partially excusing the attempted rape on the grounds that Dora was "depraved by nature" and, at 14, was "already sexy as an ape".

It reveals that Golding told his wife he had been sure the girl "wanted heavy sex". She fought him off and ran away as he stood there shouting: "I'm not going to hurt you," the memoir said.

Two years later, the pair met again and had sex in a field, with Golding again introducing crudity by quoting the girl's foreplay remark: "Should I have all that rammed up my guts?"

The author was convinced her approach to his father was a deliberate attempt to discredit him and his older brother who, coincidentally, was having sex with his girlfriend in the same field.

The literary archives opened to Carey also include a second autobiographical work and three unpublished novels.

Golding's written estate has already been productive: his last novel, the Double Tongue, was published in 1995, two years after his death.

The author's psychological experiments with his classes at Bishop Wordsworth's school, in Salisbury, caused his eyes "to come out like organ stops", according to his private journal.

He divided pupils into gangs, with one attacking a prehistoric camp and the other defending it.

In the process, Simon, Ralph, Piggy and the other characters in Lord of the Flies may have been born.