A brush with death: Why Britain's coolest art and fashion names have rallied around a victim of random knife crime

Monday night in east London members' club Shoreditch House, and a glamorous group of artists and fashion designers has gathered for a charity auction. Tracey Emin is posing for photographers in front of two drawings she has donated for the event. Antony Gormley is there too, busily repositioning his contribution – a stark black-and-white image of a human silhouette. Works by Wolfgang Tillmans, Banksy, Rankin, Ron Arad and Cornelia Parker fill the wall space. As well as the art, there is a cluster of mannequins, each swathed in pieces donated by the hottest names in fashion – Christopher Kane, Richard Nicoll, Marios Schwab and Roksanda Ilincic.

The auction begins, and with telephone bidders hanging on the line from the States, business is brisk. The Harry Potter actor Daniel Radcliffe, who seems to have turned up with his entire family in tow, is determined to get his hands on the Banksy and, after some frenzied bidding, finally wins it for £7,000. A large-scale image by fashion photographer Tim Walker goes to a New York collector for £6,500 and Gormley's piece is surely a snip at £7,000. As the cash rolls in, Will Young surveys the scene quietly from the sidelines and an increasingly vocal Tracey Emin sits perched at the bar. "It's too cheap," she screeches, "too cheap." When the hammer comes down on the final lot, the Australia-born singer Daniel Merriweather steps on stage to entertain the now boisterous party-goers.

It is a celebrity turnout that would have been a coup for any well-established charity, but this is actually the launch of an organisation, called Art Against Knives. What is even more remarkable is that it was set up by three 21-year-old students, none of whom really knew what they were doing, but who were galvanised to act after an incident last year turned their lives upside-down. "The plan was to have a little drinks party and maybe see if we could auction off some of our student friends' work to raise money," says one, "but it escalated."

Last summer Oliver Hemsley, Katy Dawe and Alice Wilson were three ordinary twentysomethings who had moved to London to study. Hemsley and Dawe were both fashion students at St Martins, while Wilson was doing a design degree at the London College of Communication. "We were all just having a brilliant summer before university," says Dawe. "We were out every night just having a laugh."

Then, on the evening of 28 August, all that changed. Hemsley decided to meet Wilson and a couple of other friends for a drink after work. He set off from his home on Arnold Circus, in the heart of London's fashionable Shoreditch, for the George & Dragon pub a couple of minutes walk away. When he turned on to Boundary Street, a group of about six local teenage boys, aged around 15 and 16, pushed aside the girl he was walking with and attacked him from behind, hitting him on the head with a bottle. Then they started stabbing him. The first knife went in through his back and into his lung. Then they went for his neck, his chest and his heart. Once they had finished, as Hemsley lay motionless and bleeding in the street, one of the attackers returned and jumped on his head. The entire assault, which had taken place just off a busy London thoroughfare in broad daylight, lasted for four-and-a-half minutes.

Hemsley, who had never been in a fight in his life, barely made a sound – he never stood a chance. But thanks to the horrified screams of the girl he had been walking with, the police and ambulance service were on the scene within minutes, whisking Hemsley to the Royal London Hospital in nearby Whitechapel. But by the time he got there, his heart had stopped beating, his spinal cord was severed and clinically he was dead.

No one knows why those boys picked on Hemsley that night. It seems that he was in the wrong place at the wrong time, the victim perhaps of a gruesome gang initiation. They couldn't have chosen a more gentle, innocuous person. Hemsley was an upbeat, funny, popular fashion student who was a regular on the Shoreditch art scene. He had grown up in a tiny village north of Cambridge and only moved to London two years before, to pursue his dream of studying at St Martins; he was due to take up his degree place just days after the attack.

If there was one bit of luck on Hemsley's side that night, it was the fact that the incident happened just around the corner from one of the country's leading trauma hospitals. ' The Royal London is home to the capital's air ambulance, so the staff there are highly skilled at dealing with severely injured people. When Hemsley was brought in, the doctors resorted to one final technique to try to get his heart beating again – a brutal piece of high-risk surgery called a clam-shell thoracotomy, which has a success rate of less than 20 per cent. To do this, they cut him from one side of his chest to the other, lifted his ribs, parted his lungs, reached in, took his heart from his body and coaxed it back to life. Hemsley had lost bucket-loads of blood, he couldn't move from the neck down, but he was alive.

It is hard to imagine how a parent would feel receiving the call that delivered that news. "It was a bolt out of the blue. I can't describe how it felt as it is too painful to recount," says Hemsley's mother, Jenny, a primary-school teacher. "In the dark days after the attack we were so frightened and so anxious but we had to keep going for Oli's sake." When Dawe received a call about it, she was so shocked that her legs gave way beneath her. "I remember having to walk past the spot where the attack had happened to get back to my house," she says. "I saw police searching through the bins. I just stopped and vomited all over the street."

A lot has been written in the media about victims of knife crime who die, but there is little about those who survive and have to carry on living with the consequences. The month Hemsley was stabbed, there were 444 hospital admissions for "assault by sharp object" (knife attacks) in England alone (there were 4,910 admissions over the year). Most will figure briefly as a story in the local paper then disappear, each victim left to fathom how to come to terms with the physical and psychological fallout. "It's been really tough," Hemsley says with typical understatement, "because there's no manual on what to do when you get stabbed. No one knew what to do. Me, my parents, my friends – we all had to learn."

Hemsley's parents moved from their village of Sutton in the Isle into a caravan in south-east London to be closer to the hospital, and his dad, also a teacher, officially retired the day after the attack. "What made it so hurtful," says Hemsley's mother, "was that it was random, totally random. If it had been for a reason – that he was carrying money, or if he'd been out drunk with a knife himself – it may have been easier to understand. But this was impossible to rationalise."

Mercifully, Hemsley has only vague recollections of the attack. "I think I can kind of remember feeling some sort of blows coming down on to my body," he says. "I'm very glad I can't remember more. Someone told me snippets about it the other day and it was horrible to hear. In the future, when I'm ready, I can ask."

The first few months passed in a blur for Hemsley, but the one thing he did know was that his friends rarely left his bedside. One of them brought a projector to his hospital room, stuck a sheet up on the wall, and his friends would all go around to watch films, read magazines and play music. Dawe went there every day. "We just did what we would always do when we were hanging out," she says. "It was never a sad atmosphere; we just kept it as normal as possible. We realised it really was an amazing thing that Oliver was still with us, so we counted ourselves lucky. It sounds like quite a weird thing to say, but we turned it into something really positive."

Hemsley spent 134 days in intensive care. When he turned 21 in October, his friends filled his room with helium balloons. At Christmas, they got dressed up, brought presents and drank mulled wine. At one point, there were more than 30 people trying to get into intensive care to visit him. The nurses had to start clamping down. "From the beginning Oli had so many visitors, and I didn't dare believe they would stick with him, but a year on and they are still there," says his mum. "They have helped us restore our faith in humanity, which I can assure you goes when your son has been violated in the way Oli was."

When Dawe and Wilson started talking about setting up Art Against Knives to raise awareness as well as funds for Hemsley's care, it was decided they would do it only if he worked on it with them. All emails were copied to Hemsley, which he monitored from his hospital bed. News of the stabbing had sent shockwaves through the halls of St Martins as well as among Shoreditch locals, and both powerful artistic communities threw their support behind it. "More and more people kept hearing about what we were doing and coming forward to ask if they could help," says Dawe. "So many people have been touched by what happened to Oliver. We had a completely overwhelming response."

Tracey Emin, who lives around the corner from where Hemsley was attacked, didn't just donate work and turn up on the night, she also personally gave him a big pile of art books. "It's so sad and appalling what happened," says the artist. "A young designer with his whole life ahead of him stabbed in the spine for what? Absolutely nothing."

When one of the creatives at global marketing company Leagas Delaney heard about Art Against Knives, the agency offered to come up with a poster design for the campaign. Someone else built them a website and someone managed to get Shoreditch House for free. And still the ball carried on rolling. In the run-up to the auction, somehow they managed to get adverts placed in the national press as well as on digital billboards throughout London, all entirely for free. It was turning into a masterful campaign.

As they worked on the project, amazing things started to happen to Hemsley. First, one of his fingers twitched a tiny bit, then his leg. "I remember the first time I moved my leg, just twitched a muscle, my dad and I cried. It was amazing," he says. "From then on," continues Dawe, "we would just sit there for hours and watch your big toe." He was moved out of intensive care and into the Royal National Orthopaedic Hospital in Stanmore, Middlesex, for rehab. By the time the Art Against Knives auction took place, nine months after the attack, Hemsley had defied all expectation and was moving around in a wheelchair. "I just took it day by day," he says. "I never wanted to hear about my prognosis because they prepare you for the worst. I just wanted to stay optimistic."

Meanwhile, the police were working to try to catch his attackers. "We were aware that various people were being brought in, being charged, not charged, questioned, released, bailed. All this kind of stuff," says Dawe.

Then, in April, one of the suspects finally made it to court: a 15-year-old local boy called Nazrul Islam. The police had found a discarded kitchen knife in the churchyard next to Boundary Street hours after the attack. It had Hemsley's blood and Islam's DNA on it. At the sentencing, Judge Roger Chapple described it as, "An entirely motiveless, mindless attack. Its ferocity makes my blood run cold." He took the unusual step of lifting restrictions on reporting Islam's name (because he was under 16) and releasing it to the press because "he [Islam] speaks with a degree of pride about his reputation with the boys, with the local community". (While Islam was on bail for the attack of Hemsley, as officers waited for forensic tests, he threatened and robbed a 12-year-old girl.)

Neither Jenny Hemsley nor her husband went to court, "I just didn't want to see the person who did that to my son." Islam was sentenced to 10 years, for GBH with intent. It was, the Hemsleys were told, a good result. The likelihood is that he'll be out in three years. I ask Hemsley what he thinks of the sentence. "Unsure," he says slowly. "They were trying not to leave me alive. There's no way in my mind you could put a knife into someone's neck, heart, back and lungs eight times, to bottle them, stamp on them and expect them to be alive... To all intents and purposes the doctors brought me back from the dead, so, yeah, it is a bit strange. But we are pleased because in Britain that [sentence] is the maximum possible."

It is now just over a year since the attack and Hemsley's progress continues. He recently left hospital and moved into a flat in Farringdon, where he lives with a carer. He has now regained enough movement in his hands to start drawing and sewing again. "The hand/eye coordination is still there," he says. "It's all a little bit wobbly but I quite like a scratchy drawing." He's learning how to navigate London by wheelchair and even laughs as he tells me all about the surgeon who took out his heart, "put it on a tray" and made it start again.

Meanwhile, Hemsley, Dawe and Wilson find themselves in the unexpected position of being directors of a successful new charity. The trio have been asked to head the prestigious Fash-Off party on 23 September, which means they will be responsible for the closing party of London Fashion Week – a party at which they will also launch a further, online, auction of 10 more pieces from well-known names from across the art and fashion worlds. Leagas Delaney has donated office space in London's Tottenham Court Road and they currently go there daily to plan the future for Art Against Knives. They are meeting lobbyists, raising questions and deciding what stand their charity should take to help ensure that what happened to their friend doesn't happen to somebody else's. St Martins, meanwhile, has agreed to hold Hemsley's place open until whenever he is ready. "So many good things have come out of this," concludes Dawe. "Oliver is always going to be dealing with it. We're always going to be dealing with it, but there's no point being angry. We've salvaged something positive from it. We don't really even talk about it much any more. We've moved on."

Fash-Off and Stimuli magazine present Art Against Knives on 23 September, when the online auction will begin on the charity's website at www.artagainstknives.com