Brideshead Revisted: How cinema is rewriting Evelyn Waugh’s classic

It is a tale of toffs, teddy bears and trouble in paradise; a saga of snobbery, sanctity and social climbing; a romance of religion, ruin and redemption. Brideshead Revisited has exerted a powerful hold on the British imagination for more than 60 years, although it's far from obvious why. Its structure is shockingly broken-backed. One of its most attractive characters disappears halfway through. An undercurrent of anti-egalitarian snobbery becomes a tidal wave. The central love story is treated by the author like a conveyancing contract. And the characters' preoccupation with Catholicism doesn't ring true. But Brideshead has Unassailable Classic status and, as the producers of a new film have found, one mucks about with it at one's peril.

The story is presented as "The sacred and profane memories of Captain Charles Ryder", and his relationship with the family of Lord Marchmain of Brideshead. Charles meets the Marquis's son, Sebastian, in 1923 Oxford, where they pursue a life of languorous decadence. Charles learns that his friend's mother is a manipulative Catholic tyrant, and his father (a convert to Catholicism) is living with a mistress in Venice. As Lady Marchmain enlists Charles to keep an eye on Sebastian, he proceeds to drink himself insensible and out of the story. Charles falls in love with Sebastian's sister Julia, who marries a Canadian arriviste, Rex Mottram. The story fast-forwards to the meeting of Julia and the now-married Charles on a cruise liner, where they consummate their passion at last. They set up home in Brideshead for two years. When his wife dies, Lord Marchmain comes home, makes a silent deathbed re-conversion to Catholicism and expires, upon which Julia renounces her life of sin and tell Charles they must part for ever. The story is book-ended by Captain Ryder's "revisit" to the big house during the war, when his company is billeted there.

With its gorgeous settings and vivid atmospherics, Brideshead Revisited always seemed destined for big-screen treatment – but has always run into trouble. In 1946, Evelyn Waugh was invited to Hollywood to discuss a "film treatment" and sell the rights for $140,000. At MGM's offices he met the proposed adaptor, one Keith Winter, who, Waugh noted with distaste, "sees Brideshead purely as a love story". He dubbed his Hollywood guests "Californian savages" and, in February 1947, sent them a memorandum explaining, with yelping condescension, the point of his book: "The theme is theological. It is in no sense abstruse and is based on principles that have for nearly 2,000 years been understood by millions of simple people, and are still so understood. But it is, I think, the first time that an attempt will have been made to introduce them to the screen, and they are antithetical to much of the current philosophy of Hollywood." The "principles" were "the operation of Grace" on human souls, the Church's power to reel in wayward adherents; and the "plans" held by God for each individual by which he or she may find redemption.

You can practically hear the studio executives' jaws dropping. The film idea was dropped. A couple of years later, Graham Greene (a Catholic convert, like Waugh) was signed up to write a screenplay. Waugh wrote to tell Greene how delighted he was. But the double-strength Papism of the enterprise never made it into production.

In 1981, Granada TV released a super-lavish, 11-part adaptation. It was filmed at Oxford, in Waugh's college, Hertford; at Castle Howard; and on the QE2, for the sex scene between Charles and Julia. V C When the BFI drew up its hierarchy of Greatest British TV programmes ever, Brideshead Revisited came 10th.

Yet there was confusion over the screenplay. On the credits, the words "Adapted by John Mortimer" appeared. This is, to say the least, misleading. In Graham Lord's biography of Mortimer, Lord explains that Mortimer's script had been "reworked by others". In Valerie Grove's more recent life, A Voyage Round John Mortimer, it's revealed that his script wasn't used at all. Derek Granger, the producer, handled the adaptation, with the writer Martin Thompson, in a kind of screenwriting-by-numbers, sticking close to Waugh's words. Swathes of Waugh prose were recited in Jeremy Irons's plangent narrating voiceover. Owners of the book could follow the screen dialogue down the page. The drama grew; what started as a crisp five-episode mini-series became a monster. It was an act of the utmost fidelity to the book – but it still played down the religious content, until the deathbed conversion of Lord Marchmain (Laurence Olivier), filmed as an earth-shaking climax.

This autumn, a film of Brideshead is released for the first time, a predictably ravishing, dreamy, aristocratic swoon of a movie, directed by Julian Jarrold. It stars Matthew Goode as Charles, Ben Whishaw as Sebastian, Hayley Atwell as Julia, Emma Thompson as Lady Marchmain and Michael Gambon as her errant husband. Fans of the book who cannot wait for its release in October should check out the trailer on YouTube, where they'll find some remarkable differences from the book.

First, Sebastian and Julia appear to be conducting an incestuous relationship that becomes a ménage a trois with Charles. Second, Julia shows up, under a parasol, in the Venice scenes. Third, Lady Marchmain seems concerned only with marrying off her daughter to the cluelessly non-Catholic Rex. Fourth, there's a wildly misconceived strand of sexual intrigue, most fatuously when Lord Marchmain leans back on a sofa with one arm around a coquettish Julia and the other around a pouting Sebastian and twinkles at Charles with the words: "What a lot of temptation..." Fifth, the religious theme is hinted at only by a dropped crucifix. Sixth, Sebastian shouts: "You never wanted me – you used me to get to my sister!" (In the book, by the time Charles and Julia get it together at sea, Sebastian has vanished into alcoholism and a monastery in Morocco.)

All this is shocking for Waugh purists. The message board on the IMDb website is a-twitter with denunciations by Waugh fans. "Andrew Davies needs a reality check," reads one. "And a slap in the face like he's given to Evelyn Waugh by turning his masterpiece into a cheap romantic farce."

Davies – the nation's foremost adaptor of classic novels into racy screenplays – is indeed one of the names credited with the screenplay, the other being Jeremy Brock. But industry insiders now hint that Davies's script was never used, and that Brock is solely responsible. Davies isn't able to comment: he has, it seems, signed a contract forbidding him from saying anything.

The mystery deepened when a row broke out last week. Mortimer told Radio 4's Today programme of his fears about the movie. He'd heard, he said, "terrible rumours" that key themes from the book had been left out of the film: especially God, homosexuality, and Aloysius, the teddy bear Sebastian carries everywhere. "It is entirely a book about God and homosexuality," Sir John declared to Brock, adding: "If you were to take out the teddy-bear, it would be an outrage to Evelyn Waugh."

The curious thing is, just about a year ago, an audience of several hundred at the Hay Festival were confidently informed that Aloysius the bear would definitely not be appearing in the movie. The bringer of this sorry news was Davies. A year later, on Today, Brock smoothly reassured listeners that the bear was in the film, as were the themes of God and homosexuality.

Such battles between writers and producers to preserve the integrity of a 60-year-old classic! It was strange to hear Mortimer exhorting listeners to "Read the book!", but one can understand his frustration. Less understandable is his (and Brock's) insistence that homosexuality is a central theme of the book. It isn't. Charles and Sebastian's relationship is intense, all-consuming and homoerotic certainly, but there is no internal evidence (so to speak) that they ever have sex.

The wonderful Anthony Blanche, stammering, bitchy, sophisticated, is clearly and resplendently homosexual, a representative of the poseurs and prancers of the Hypocrites Club, where Waugh could sometimes be seen lying on the sofa with a gentleman friend, their "tongues licking each other's tonsils". Charles and Sebastian are more chaste. Their true relationship is expressed in a rapturous passage that is a key to the book: "That summer term with Sebastian, it seemed as though I was being given a brief spell of what I had never known, a happy childhood, and though its toys were silk shirts and liqueurs and cigars, and its naughtiness high in the catalogue of grave sins, there was something of nursery freshness about us that fell little short of the joy of innocence."

Innocence, hedonism, self-indulgence, treats, Oxford, glamour – they all inform Brideshead Revisited. The memory of the life their author had led, 20 years earlier, left a vast, psychic ache in him. For most of 1943, Waugh was sunk in gloom. He was fed up with army life. After serving in Crete with the Special Services Brigade, he had spent a year waiting to be given a company to command. None was forthcoming. It was agreed among the senior officers that the author-turned-soldier was spectacularly ill-equipped to command ordinary soldiers, because of his "total incapacity for establishing any sort of human relations with his men". He was, all agreed, a 24-carat, card-carrying shit. His rudeness, his dislike of the working classes, his fondness for bullying and horror of social contact with strangers made him, in the words of his commanding officer, Lord Lovat, "a total misfit".

For a year, he'd hung out in a London office,drinking gallons of wine with friends. In July, his father Arthur died. Evelyn's wife and children remained in Combe Florey, Somerset and rarely contacted him. "I should like to feel," he wrote to his wife Laura, "that, once or twice a week, you felt enough interest in me to write and say so... If by any chance the children should die, do come to London. I miss you."

Then he received the final kiss-off. He was advised to resign from the Commandos "for the Brigade's good". It wasn't just rejection and bereavement that brought him low; it was the condition of England at this point of the war, and the predictions of its aftermath. "Everyone I meet is despondent about the future," he confided to his diary. Wherever he looked, life was grotty, grey, sloppy, utterly lacking in style, grace and chic. By the year's end his nerve had broken. He asked the army for leave, and travelled to Chagford in Devon. In that frame of mind , at the beginning of February 1944, he began to write Brideshead.

Waugh later accepted that it was regret for the world he was about to lose that made him write a novel so unlike his bitter, blackly comic idiom. When he revised the book in 1959, he was careful to trim away what he called "a kind of gluttony, for food and wine, for the splendours of the recent past, and for rhetorical and ornamental language". But there has always remained enough of that gluttony and ornamentation to satisfy readers who never experienced it themselves. The book was, and remains, a triumph of the imagination because Waugh, in 1944, twined together a dozen matters that were crucial to him: Oxford, male friendship, grand families, the erosion of the aristocracy, the uncomfortable sense of being an outsider in a strange land that he'd felt in Oxford and later felt (much more sharply) in the army; the world of 1920s student preciousness – the gay stammerer, the teddy-bear carrier – that was gone for ever.

Humphrey Carpenter, in The Brideshead Generation, identifies elements of Waugh himself in the characters of Charles the outsider, Sebastian the faun-like innocent, Anthony the dandy, even Mr Ryder senior, Charles's father, with his fondness for winding up strangers. What drives Brideshead Revisited is the sense of personal passion and grievance that jumps off the page. Even the snobbery on display – when Charles watches Rex Mottram choose the wrong glass from which to drink champagne – still works. His nostalgia for Oxford remains a thing of beauty. He was writing in rapturous elegy about what he loved, twined around what he hated. That's why Brideshead is such an exceptional read.

One cannot, however, play down the book's religious element, because religion played a crucial part in the book's genesis. Four months after Waugh's father died, he visited his old Oxford friend Hubert Duggan, who was dying at 39. A lapsed Catholic who'd lived with a mistress, he was considering rejoining the Church but was afraid it might seem like a condemnation of his life with the now-dead girlfriend. He was conflicted and needed a priest. Waugh found one, and his old friend was absolved of his sins and given the last rites. Waugh was moved to see him make the sign of the cross and accept redemption.

The writer's own father died too suddenly for his son to be reconciled to him. Duggan's last-minute salvation and Waugh's sadness for his father are pulled together in the deathbed conversion that climaxes Brideshead. It's an intensely personal moment for a writer who was feeling in dire need of redemption. Amid all the teddy bears, the wine, the lovers and the Bentleys that flow through these pages, that was, for him, the only thing that mattered.

'Brideshead Revisited' is out in the autumn