The voice is quavery and hesitant, the sound of a frightened, exhausted young man. The trebly nature of the recording - on a cassette, over the telephone - makes him sound old, paper-thin, and accentuates the slight hitch in his voice. For he is talking, quietly and surely, about his own self-destruction: "I can't drink, I can't, like the doctor said if I drank anything even remotely like the way I've been drinking for the past however long, I've got six months at the absolute outside to live."

It's 20 January 1978. There is a snowstorm in New York. The previous day, Sid Vicious slipped into a valium and methadone coma during a flight from the west coast and was rushed off the plane into a hospital in Jamaica, Queens, hard by JFK airport. A few days ago, he was the bass player in the Sex Pistols, playing to more than 5,000 people in San Francisco's Winterland. Now that the group has split up he is all alone, very lonely, and fearful of the future. The only person to contact him is Roberta Bayley - the doorperson at the city's CBGB club and a successful photographer, with credits including the first Ramones LP, who befriended him during the Sex Pistols US tour.

The blizzard is so severe that no one can get out to Queens from the city, so she calls him, in an act of humanity tinged with the demands of reportage. The Sex Pistols split is big news, so she tapes the conversation, just in case.

Like any reasonable person, Bayley is appalled by Sid's headlong flight into oblivion. "Oh well, then don't drink, you asshole," she chides. "You have to straighten out for a while." No chance. "I can't straighten up," Sid replies, his voice cracking. "I just can't be straight."

Later, he simply concludes: "My basic nature is going to kill me in six months." In fact, Sid lasted double that, dying of a heroin overdose in the early hours of 2 February 1979. He was internationally notorious, and only 21.

I included a transcript of the Bayley tape in my history of punk, England's Dreaming, but it has never been broadcast before now. You can hear extracts from it - along with fresh interviews - in a new BBC Radio 4 documentary that coincides with the 30th anniversary of Sid Vicious's death.

Over the decades, Sid has percolated through the culture: there are Sid dolls, thousands of photos on the internet, appearances in The Simpsons, and Gavin Turk's sculpture, Pop - a self-portrait in the guise of Sid and a high point of the Sensation show at the Royal Academy in 1997.

Sid has become a romantic hero. Like James Dean, nobody really cares what he was like, because he took such a good picture and, according to the script, flamed out so spectacularly. Sid did not care: he took a bad idea - the rock'n'roll suicide theatrically rehearsed by Bowie and Iggy - and ran with it all the way to the other side.

Produced and hosted by his teenage friend John Wardle, better known as Jah Wobble, In Search of Sid aims to go behind the image and humanise the icon of punk. "Sid was unformed," Wobble remembers. "He didn't have any boundaries and he didn't have any role models. Before he died he had become a complete liability. In the past I just felt anger and irritation when I thought of Sid. But I now feel a strong element of compassion. At the end of the documentary I felt that a job had been done, for all of us who knew him. I made myself love him retrospectively."

Wardle's story starts when he met Sid, then known as John Beverley, in late 1974. Along with his friend John Lydon, Beverley was attending Kingsway College of Further Education in Holborn, central London, a place where the expelled, the difficult and the intelligent could take O- and A-levels.

Lydon had another friend, John Grey, and, following Wardle's example, the four Johns began to haunt the Kings Road. They were all in their late teens, from north or east London, and this was a new part of the capital to discover. "We were all bright-eyed, looking to have fun," Wobble says; "a bit like the Marx Brothers.

"In mid-to-late 1975, the nicknames came into play. It was a crucial time. Everything was really magnified. One day, John Lydon disappeared and said: 'I'm in a band'. We were all into black music - the only rock we liked was Can, Krautrock, the Who - so this was a real surprise."

Three of the four Johns were transformed by pseudonyms that, beginning in teenage jokes, became international news. Lydon became Johnny Rotten, thanks to Sex Pistols' guitarist Steve Jones; Beverley became Sid Vicious, thanks to Lydon, Wardle became Jah Wobble, thanks to Sid.

Sid was named after Lydon's pet hamster, recalling the Lou Reed song that, with its slicing guitar, kicked off the Transformer album. It was a laugh, because Sid wasn't Vicious then: he was goofy, funny, very style-conscious - a Bowie boy. As the Slits' guitarist Viv Albertine says in the documentary, he was "kind of sweet really".

But he wasn't called Sid Sweet. Vicious was a strong name to be saddled with. The script was set and, like many scripts, it took over the actor to the point where person and persona became fatally blurred. "Be careful what you set yourself up for" should be one pop culture motto, and Sid was more vulnerable than most.

Born on 10 May 1957 as Simon John Ritchie but also known as John Beverley, Sid was the only child of mother Anne. It was a peripatetic, poor childhood, as they moved from Tunbridge Wells to Bristol and finally Stoke Newington in north London. When Sid turned 16, she threw him out on the streets. When I interviewed Anne Beverley in 1988, she remembered her son with pride, but her anger came through. "I remember saying to him: 'It's either you or me, and it's not going to be me. I have got to try to preserve myself and you just fuck off.' He said: 'I've not got anywhere to go,' and I said: 'I don't care.'"

Sid's family life was, according to Wobble, "a big black hole. When I met his mother at that time, she had no interest in his life. She didn't even know he was attending Kingsway. She was into the hardcore drug thing - heroin and opiates - which was all-embracing, that was her life."

As we speak, Wobble recalls, for the first time, a chilling incident. Even before his notoriety, Sid had "a weird, brooding quality. He would loon about, he was very bright, but he had another side. He was very hurt, I now realise. Even then he made me feel cautious. An hour or two of his company was enough.

"I sensed his dark side as early as 1975. He had a counsellor at Kingsway: they had obviously identified him as a kid with problems. He'd already said that he was going to kill himself. The counsellor had told him to bring a friend along so we both went one day, for a laugh.

"The counsellor said: 'John says he's going to kill himself,' and I said: 'He might as well end it all.' Sid nodded his head, very gravely. The counsellor was a very earnest, Hampstead bloke, and he didn't know what he was dealing with. His mouth was open. It was supposed to be fun, but as I came out, I thought: 'Oh God.'"

Sid starts to enter the public domain during the spring of 1976. He is pictured at the Nashville pub in April, watching the Sex Pistols attack their audience. He is implicated, along with Wobble, in the violence directed at journalist Nick Kent during a Sex Pistols show at the 100 Club.

The suggestible teenager was being shaped by malign forces. "Once he got into the squat world," Wobble remembers, "he lived in some very depressing places. The zeitgeist was nihilistic. There were hard drugs around. It was that time and generation: a reaction against the 60s."

Sid might have begun, in Albertine's words, as "softer, sheepish and shy" but as punk became a national phenomenon, he started to grow into his role. At the September 1976 100 Club Punk Festival, he took the stage as the drummer for Siouxsie and the Banshees, banging out a simple Mo Tucker/ Velvet Underground pattern.

The next day, during the Damned's set, a glass was thrown and a young woman received severe eye injuries. Sid was arrested and packed off to Ashford Remand Centre. While there, he wrote a letter to Albertine: he was reading a "book about Charles Manson that Vivienne Westwood lent me". He found it "quite fascinating".

Sid became the Sex Pistols ur-fan. Encouraged to run wild, constantly drunk, he became the figurehead of the new movement, inventing the pogo dance and coming out with pithy, nihilistic statements that defined the new age.

In Jonh Ingham's seminal October 1976 Sounds article, 'Welcome to the "?" Rock Special', Sid dominated the pull quotes: "I didn't even know the Summer of Love was happening. I was too busy playing with my Action Man"; "I've only ever been in love with a beer bottle and a mirror."

Sid formed a band with Albertine, the Flowers of Romance. He learnt the bass by listening to the first Ramones album: fixing on the bump and grind pattern from I Don't Wanna Go Down to the Basement, he would apply it to nearly every song that he touched.

In February 1977, he stepped into the role he felt he was born to play, replacing Glen Matlock as the Sex Pistols bassist. Within a few months he had hooked up with Nancy Spungeon, a New Yorker who, although slightly younger, was more worldly than him. Her appetite for self-destruction matched, if not exceeded his own.

They genuinely loved each other, but Nancy had a disastrous effect on Sid. Already a junkie, she reintroduced him to the drug and so Sid was cast into his last, and most enduring, phase: that of leather-clad, random destruction machine.

Subtlety had never been Sid's forte and he was not hired for his dexterity (and, in fact, played on few Pistols records): he was John Lydon's friend and, as far as manager Malcolm McLaren was concerned, the perfect assistant in the Sex Pistols' career as national and international outrages.

Wobble says now: "Sid was offered up as a sacrificial lamb by the people around the Pistols. None of them would have gone over the top. He was their kamikaze pilot, and they were all too happy to strap him and send him off."

Sid's behaviour peaked during the group's final tour of the US. Forcibly withdrawing from heroin, he was out of control. Whether clubbing an audience member with a bass in San Antonio, or carving 'GIMME A FIX' on his chest in Dallas, he turned the Pistols into a living circus. Talking to Roberta Bayley after Lydon left the group, Sid said he thought he was the most "Sex Pistol" of them all. In Wobble's words, he embodied "everything in punk that was dark, decadent and nihilistic".

But this was also the moment when punk truly became pop. During 1978, McLaren kept the Pistols going without Lydon. As Sid dissolved further into a hail of drugs, he had a top 10 record in July with his radical cover of My Way. As the single slipped down the charts, Sid and Nancy moved to New York, never to return.

Ensconced in room 100 of the Chelsea Hotel, they sought oblivion, and Nancy found it on 12 October, when she died from a knife wound. Sid was arrested for murder but it was very unlikely that he would have deliberately killed her: it was probably a case of mutual provocation resulting in a stabbing, compounded by negligence.

The rest was a ghastly mess. Sid was charged and let out on bail. After attempting suicide, he spent three days in hospital. In early December, he bottled Patti Smith's brother Todd and was sent to Rikers Island prison for two months. On the night he was released, he took some extremely pure heroin and overdosed during the night.

After he died, two Sex Pistols singles were released with his vocals. Both Something Else and C'mon Everybody reached the top three - becoming the decade's two bestselling Pistols songs.

Now that punk has become mythic, so Sid has become its archetype: the heedless young man who went all the way, who told the world a brutal truth. The reality was far grimmer. The most frightening thing about Sid's conversation with Bayley is that he knew that he was killing himself, but that he had no power to avoid the inevitable.

Sid Vicious was not stupid, but he did not have any emotional resources with which to deal with fame. As Wobble says: "John Lydon kept a link with his past, and that saved him, but Sid had no past." Sid was a lost boy who, like Peter Pan, never grew beyond childhood, and his spectacular demise was both exploited and unmourned.

"I felt like giving him a proper funeral because no one ever did," Wobble says today. "It's like when someone dies at sea, and you throw a wreath overboard. That's what I'm doing: throwing the wreath. I wanted to state what this boy meant to the world, and that he was a good boy."

• In Search of Sid will be broadcast on Radio 4 on 20 January. The England's Dreaming Tapes, a collection of interviews from Jon Savage's England's Dreaming, will be published by Faber in autumn 2009

No future? What the pistols did next

Johnny Rotten

Left the band in 1978, forming critically lauded post-punk act Public Image Limited shortly after. After putting PiL on hold in 1993, he became a regular on TV and radio, appearing on I'm a Celebrity...Get Me Out of Here and presenting nature shows. Last seen advertising butter. Lives in Los Angeles .

Steve Jones

Worked with Malcolm McLaren and Paul Cook on the soundtrack to The Great Rock'n'Roll Swindle before forming the short-lived Professionals with Cook, and fronting the Neurotic Outsiders. Has hosted Jonesy's Jukebox, a daily radio show in LA, since 2004.



Paul Cook

After the Professionals, Cook produced Bananarama's debut album, Deep Sea Skiving, in 1983 before starting the Chiefs of Relief. Now plays with alt-rock trio Man Raze.

Glen Matlock

Matlock formed the Rich Kids with Midge Ure, then went on to play with Iggy Pop and the Damned, before rejoining the Pistols for their mid-90s reunion shows.