For a secretive man it was a very public validation. In February 1976, more than 20 million Britons crowded in front of their television sets to watch someone they’d never heard of reinvent a sport they scarcely understood. Figure skating’s gibberish lexicon, with its lutzes and loops, meant nothing before John Curry took to the ice. In five hypnotic minutes gliding across the ice, he transformed a discredited Olympic event into a glorious art form. He had planned it that way, but he never expected to pay such a heavy price.

John Curry was 26 when he seared his name into the record books. In just two months he won the European, Olympic and world figure skating titles. Within hours of securing a gold medal in Innsbruck, however, he told a marauding press that he was gay. The revelation raced around the world. Soon after, Curry appeared to vanish. Not until 1994, when he was dying of Aids at his mother’s Warwickshire home, did I chance across his name again.

Near-penniless, he invited the Mail on Sunday to take pictures of his ravaged body. Gone was the glow of 1976. In its place were sunken eyes and blotchy skin. Curry’s courage, though, was undimmed. All around him, celebrities hid from their sexuality – sportsmen especially. With months left to live, this genius stepped into the light again. But where had he been? And who was he?

For the past two years I have been trying to investigate this tortured, brilliant man for a book I’ve been writing. It has not always been easy. As one of Curry’s friends warned me: “You are going in search of a black hole.” Yet as I put the finishing touches to the book, it seemed more essential than ever. Vladimir Putin demonised gay athletes in the run-up to the Sochi Olympics. A sports person coming out is still a sadly rare event.

Yet at times it felt as if Curry – certain that he was dying – had deliberately made himself hard to follow. At least one friend had been asked to burn all his letters. After his death, a collection of diaries was apparently destroyed. A bleak memoir, written in the mid 90s by Curry’s former producer incurred such wrath from the dead skater’s supporters that it was withdrawn and pulped. And when tracking down Curry’s fellow-skaters – and lovers – in the United States, the scale of the catastrophe which had engulfed him became apparent. Most of the men who “knew” him are long dead. During the 80s and 90s more gay men died of Aids in America than Americans had died in Vietnam. Toxicity hung around John Curry like mist over ice. Why?

The answers began to emerge in the bungalow where he died; the home he bought for his mother Rita, now 100. There in the roof space, bundled inside cardboard boxes, were the remnants of Curry’s life. The passports – every page a blizzard of red ink – which confirmed his rootlessness. Tarnished trophies (“1958 – John Curry – 3rd”); congratulatory telegrams, coded Valentines and countless photographs. There was Curry tanned on a Long Island dune. Curry on a horse. Curry, in his pomp, dazzling the Royal Albert Hall and the New York Met. And on one nameless postcard a naked man lying face down on a beach, his buttocks exposed to the sun. But among all these clues and shards of his life, Curry’s childhood was nowhere to be found.

Rita knows why. She, too, has kept little trace of her past, preferring to cloak sadness in unsentimentality. No school reports and few family photographs survive. Of her husband Joseph – John’s father – only one picture remains. “There were some awful things but they’re shut away,” she said. I dug harder, however, and from the inquest reports, John’s later disclosures, and Rita’s guarded revelations, the skater’s childhood story came into focus.

High hopes: at the 1976 Innsbruck Winter Olympics. Photograph: Colorsport/REX Photograph: Colorsport/REX

During the Second World War, Joseph Curry was incarcerated in a German POW camp for three years before escaping back to Britain in desperate ill health. Before the war he ran his own thriving company in the West Midlands, and established a family, with three sons, in an Edwardian pile south of Birmingham. Behind the comfortable facade, however, Curry’s father was a hard-drinking depressive plagued by insomnia. When his musically inclined youngest child sought his blessing to attend ballet lessons, permission was flatly denied. Skating, on the other hand, stirred no concern and – escorted by the indefatigable Rita – John began the lessons that would transform his life. Over the next eight years Curry’s father saw him skate just twice. By the time John was 16, in 1965, his father was dead.

To this day, Rita insists Joseph’s death was an accident. The coroner thought differently. Between Christmas and New Year, Joseph’s body was found sprawled in a London hotel room. No one could explain why he was there, but an inquest determined that he had taken his own life with an overdose of the sleeping drug, chloral hydrate.

“We were delighted. We were happy. We were free of him,” Curry spat bitterly, years later. But he was wrong. Just like his father, the teenage Curry had dark contemplations. “I don’t think anyone will ever love me,” he told a friend. “I’m like a sick-headed child.” In 1969, as he headed for London set upon a skater’s life, solitude – and illicit sexual awakenings – would merely compound a lifelong penchant for existential despair.

“It frightens me to realise all the horrible things I think when I am in such moods,” he wrote. “I would like to do something really perverted or kill someone with a knife or something. I don’t know what will happen to me. I’m having the worst dreams I have ever had.”

Thankfully not all of John’s letters vanished. In the course of my research more than 200 turned up, each one characterised by acid wit and abysmal spelling; each dripping with unhappiness. “Do you think I shall ever be happy?” he asked his first lover. “Everywhere I go I get miserable very quickly. I know that I’m pretty difficult but I’m not as horrible as all that am I?”

As Curry’s career took off, however, his “difficult” reputation was becoming well known – and not without reason. Instinctively, as a skater, he baulked at the brawny athleticism of a sport dominated by Eastern Europe. Few coaches warmed to his alternative musical style – or his sexually suspect “arm-waving”. Those who didn’t were peremptorily sacked. “You will never make it as a skater or as a man,” one illustrious casualty warned him. But a few years later Curry was the champion of the world.

By the mid-70s he had also begun a lifelong love affair with America. For 20 years he’d been stifled in ice rinks in the UK. Like many dedicated athletes, Curry was as socially underdeveloped as a prison lifer. Now that he was famous, and free to pursue his vision, his mood swings intensified. He also had access to all the temptations open to a star athlete in a world city.

Among close friends, as his choreography grew ever more sublime, he could be savagely amusing. Among his troupe of skaters, plagued by dodgy managers, tiny stages and patchy reviews, he visibly darkened. “He was corrupted by rage”, says lifelong friend Penny Malec. He was also experimenting with drugs, and developing a taste for extreme sex. In 1978, after a mysterious, violent assault near Earl’s Court, Curry’s pioneering London stage show folded. Soon after that – by this time awarded an OBE – he moved quietly to New York.

Yet in Manhattan, too, Curry’s self-destructive urges found vent. During a Broadway ice show he collapsed and was carried from stage. During a performance of Brigadoon, he threw a dirk into the stage floor and fled the theatre. Again and again, he drove himself creatively only to collapse in weary self-loathing at the moment of triumph. “He is a seeker who seems to be moving on the air,” said the New York Times after his 1984 shows had left audiences gasping in tearful disbelief. “He is a lone figure on a glacial plane.” And yet, behind the scenes, his diva-like bullying periodically reduced all his devoted skaters – male or female – to sobbing wrecks.

“He’d go to an anorexic and tell her she was fat,” says skater Adam Leib. “He’d go to the best athlete in the group and tell him he was not worthy He wanted you to feel the hurt he was hurting. He lived by torment. He was adept at speaking without a word. Just his facial inflections could tear you to shreds.”

In the summer of 1984 – the zenith of his creative output – Curry returned to London for a series of shows at the Royal Albert Hall. On opening night, despite water that wouldn’t freeze, his work brought thousands to their feet. Alongside his 12 fellow skaters, Curry had returned to take bow after bow. “Courageous, gripping, incredible”, said the papers. Suddenly, behind the scenes, everyone – Princess Margaret among them – wanted to meet him. Finally, every homophobic whisper had been silenced. But for Curry, it was not enough. A few months later, while performing in Copenhagen, he faked an injury and fled back to the United States. Weary from constant performing, worn down by commercial and creative pressures, he’d finally reached the end of his line. “None of us believed he was hurt,” said one witness. “It was a collapse. No more. Everyone has a limit. Only his heart was hurting.”

In the bruised aftermath, Curry laid low and licked his wounds. Putting his lifelong vision on stage, alongside a full orchestra, had been financially ruinous, and his company was more than $1m in debt. There would be other successes, albeit in a minor key, but Curry’s appetite for innovation was done. He was also very lonely. By Christmas 1987 he knew how he would die. New York had granted him artistic freedoms. But for a gay man in Greenwich Village there had been other freedoms, too. Curry had embraced them with the abandon that characterised an entire generation.

As a teenager in London he had been restrained by the law and by self-doubt – “Lots of people watch me, and stare at me, but no one talks to me,” he said. In secret Manhattan, and out on the gay enclave of Fire Island, no such rules applied. Here, undoubtedly, Curry was at his happiest. With no pressure to perform, and in the company of only his closest friends, he read Dickens, walked on the sand and cooked inventive meals in glorious beachside condos. “He was a very beautiful man,” says one lover from this period. “But he seemed very lonely.”

Now in his late 30s, Curry had never had a long-standing partner. Periodic infatuations with his fellow skaters invariably ended in tears, most of them his own. As the 1980s petered out and he pushed hard to find work as an actor, many of those former friends and lovers began to fall ill and die. Desperate for funds, he took work playing Buttons in a Liverpool pantomime. Anything to prevent him from going back to the ice. Anything to keep his mind off the knowledge that he, too, was now HIV positive , and that – if lucky – he had just six years left to live.

While his strength held, he stayed in New York. Around Manhattan, generous (mostly female) benefactors were never far away. His AZT medication would be paid for, and there would always be a free room or apartmentwhen required. “I don’t know how anyone could not have fallen in love with him,” says his lawyer and friend, Patricia Crown. “There was a beauty about everything he did.” But by 1991, full-blown Aids was eating his beauty away, and that summer he returned home to his mother’s English country garden.

“I am peaceful,” he told his friend, Cathy Foulkes. “I love being at home again and not having to teach and skate is a welcome relief to this old body. This is not a very uplifting letter, but dear Cathy, do not worry or be sad. I have had an extraordinary life – by any standards - I’ve met with great success and happiness – and at times the reverse. So keep your pecker up.”

In mid-April, 1994, aged just 44, Curry’s indomitable will could carry him no further. “I never wanted a long life,” he’d told the actor Alan Bates. “I just hope I have done something with it.” Eighteen years before, in February 1976, he had done something that had touched an entire nation. Go and find it on YouTube. Only the flintiest of hearts will not be weeping before he stops, kneels on the ice, and smiles as bouquets shower at his feet.

Alone – The Triumph and Tragedy Of John Curry by Bill Jones is published by Bloomsbury, £18.99. To order a copy for £15.19 with free UK p&p go to guardianbookshop.co.uk or call 0330 333 6846