At the poignantly ambiguous end of The Graduate, Dustin Hoffman and Katharine Ross leap aboard a bus and ride off into the sunset leaving cinemagoers to speculate on what the future holds for the young lovers.

Far stranger than fiction, though, was what became of Charles Webb, the author of the novel on which the film was based. Webb had sold the rights to his story for $20,000. It was a paltry sum given that the film went on to gross more than $100 million. Many years later, when a British newspaper compiled a list of “the world’s biggest mugs and the blunders that cost them a fortune”, Webb was alongside the record company executive who turned down the Beatles and the man who invented the digital audio player but let the patent lapse.

Yet as a dreamer whose anti-materialist philosophy took its cue from John Lennon’s famously impractical line “Imagine no possessions”, Webb could not have cared less, devoting his adult life to refusing to bow to the pragmatic compromises of conventional existence. He began as he intended to go on, by giving away his tickets to the star-studded premiere of the film of his novel. Then he hired a lawyer to prevent the words “By the author of The Graduate” from appearing on the cover of his next book. It was “exploitative”, he said.

His publishing royalties were donated to the Anti-Defamation League and a Rauschenberg drawing and a valuable original Warhol print were donated to other non-profit organisations. He turned down his father’s inheritance and once he had got into the swing of renouncing the trappings of success there was no stopping him. His fee for the film rights to The Graduate helped to fund the purchase of a bungalow in Hollywood. A week later he handed the keys back to the estate agent and told him to give the property away. “Owning it was just unexplainably oppressive,” he said.

A second attempt at settling down led to the purchase of a three-storey house in Massachusetts. After a few weeks that too became “oppressive” and he gave it to the Audubon Society. A third house in upstate New York was given away in 1976, possibly to Friends of the Earth or perhaps handed back to the agent again. He couldn’t recall.

“It didn’t feel like a big deal at the time. We just felt more comfortable living a fairly basic lifestyle,” he said. “When you run out of money it’s a purifying experience. It focuses the mind like nothing else. You sometimes regret not being the kind of person who sorts out savings bonds or insurance policies. But you reach a point when you have flashes of insight into things.”

He hired a lawyer to prevent the words “By the author of The Graduate” from appearing on the cover of his next book. It was “exploitative”, he said.

Freed of material possessions, Webb and his wife Eve Rudd, whom he married in 1962, lived in contented penury, taking menial jobs as cleaners, cooks, fruit-pickers and supermarket cashiers. At one point they crossed the Atlantic on the QE2, exporting their VW bus with them, and settled in a nudist colony in France. They had intended their two sons, John and David, who both survive their parents, to attend French schools, but decided to educate the boys themselves.

Back in America they continued to lead a peripatetic life, dodging the educational authorities whom they feared would force their children to attend school. There were more nudist camps, including one where Webb and his wife were appointed managers.

From left, Charles Webb, producer Lawrence Turman, and director Mike Nichols on the set of The Graduate, 1967.

Webb continued to write novels, in the distinctive wry and modulated style he had perfected in The Graduate. Eve changed her name to Fred and the couple divorced in 1981 as a protest against “the inequality of women in marriage” but continued living together until her death last year.

“My parents went out of their way to subvert conformity in any form,” said David. “They convinced me to be a punker when I was 13. They encouraged me to the point of taking me to a hair salon and having my hair bleached white.” Webb and his wife were delighted when David became a performance artist, who once cooked and ate a copy of The Graduate with cranberry sauce for a Thanksgiving dinner. John works in the petroleum industry.

“We have led the most chaotic, illogical, irrational lives,” Webb admitted. “Although the more I look at it, the more I can see that there is a bizarre order to it all.”

Charles Richard Webb was born in San Francisco in 1939, the son of Richard Webb, a wealthy doctor, and a socialite mother. He grew up in the upmarket Los Angeles suburb of Pasadena, but came to detest the world of privilege in which he was born. “I have blocked out almost everything that happened to me in childhood because I just remember it as being one endless depression,” he said. “I was sent to prep school, then a small Ivy League college, choices made for me on the basis of how it looked. That’s partly what The Graduate was about. I was just a mess — a manic-depressive, neurotic kid.”

He graduated from Williams College, Massachusetts, with a degree in literature and was awarded a creative-writing grant from the college. The result was The Graduate, written partly to win favour with his mother. “She was always reading books so I thought I’d see if I could write one,” he said. “I was looking for crumbs of approval from her. But it didn’t work.”

The disapproval was unsurprising given how he poured his disillusionment with his upbringing into the book. Benjamin Braddock, played by Hoffman in the film, was clearly a self-portrait and his father was horrified to recognise himself as the hearty and uncomprehending Braddock Sr. “He was appalled that I could have brought such shame on the family,” Webb said.

At one point they crossed the Atlantic on the QE2, exporting their VW bus with them, and settled in a nudist colony in France.

The novel departed company with real life in one respect, for there was no affair with an older woman like Mrs Robinson, who was played in the film by Anne Bancroft. The character was an amalgam of the bridge-playing wife of one of his father’s medical colleagues about whom he fantasised and Eve Rudd’s mother, who had forbidden her daughter from seeing him. Elaine, with whom Benjamin elopes in the book, was Eve, of course. “Many of the scenes are actual dialogue from our late teens and early twenties,” Webb admitted.

The Graduate was published in 1963 with a cover announcing that it was “a novel of today’s youth, unlike any you have read” and was well reviewed.

The book’s deadpan dialogue, which Webb later revealed was influenced by seeing Harold Pinter’s The Caretaker with Donald Pleasence in London in 1960, was particularly praised. David Denby wrote in The New Yorker that Webb had “one of the surest instincts since Dashiell Hammett for material that can be easily adapted in popular movies”. Larry Turman, the Hollywood producer, agreed when he purchased the film rights after picking up a copy of the book at an airport shop, as did Buck Henry, the screenwriter, who admitted that he had lifted 80 per cent or more of the dialogue straight from the book’s pages.

Webb was initially excited about the film, but was soon as disillusioned with Hollywood as he had been by his parents’ values. “I went on the set once. We thought there was a great fraternity waiting for us. There wasn’t,” he said.

In 1999 Webb and his former wife settled in Britain. “We didn’t know anyone here. We just thought it would be a nice place to hang out,” he said with characteristic disregard for anything as bourgeois as a plan. Living above a pet shop on the south coast near Brighton, he began writing again and his 2002 novel New Cardiff was made into the film Hope Springs, starring Colin Firth and Minnie Driver. He gave his advance for the book to the artist Dan Shelton, who achieved notoriety when he used the money to mail himself in a sealed box to Tate Britain. Soon afterwards Webb was reported to be in rent arrears and applying for benefits.

For years Webb refused to write a sequel to The Graduate because he had also signed away the film rights to any further books involving the same characters. Eventually he relented and wrote Home School, which found Benjamin and Elaine living a life that drew on the Webbs’ own post-Graduate experience. The Times took up his cause, serialising the manuscript and putting him in touch with Random House, who published the book in 2007.

The advance enabled him to clear his debts but there was no regret about missing out on the riches that The Graduate should have brought him. “If I’d had $100 million it wouldn’t have taken me that much longer to spend than $20,000,” he said. To Webb, the reasoning made perfect sense.

Charles Webb, novelist, was born on June 9, 1939. He died of unknown causes on June 16, 2020, aged 81