The war zone: How the notorious London neighbourhood they call the 'V' is fighting for its life

One year on from Ben Kinsella's murder, the area of London's King's Cross where it happened – known simply as the 'V' – is as bleak as ever. Is there any hope for the youngsters growing up in this brutal atmosphere? A man called Beef, who spends his days patrolling its streets, thinks there is

What pained Ben Kinsella's parents most about the appalling CCTV footage of his final moments was the manner in which he kept walking, seemingly with an air of nonchalance, after his killers had fled.

Stabbed 11 times in five seconds, including through a shattered rib and into his heart, the 16-year-old could be seen wandering across the North Road in Islington as a foul patch of inky red spread through the back of his white shirt. To family and friends, as to the public, it was the incongruity between Kinsella's steady gait and the horror of what had happened – and what was to happen – that was most shocking, and most unbearable, about those grainy images.

On 12 June, Jade Braithwaite, 20, Juress Kika, 19, and Michael Alleyne, 18, were each jailed for a minimum of 19 years for the murder of Ben, the younger brother of former EastEnders actress Brooke Kinsella. They chased him down after a scuffle broke out in a local bar between people Kinsella hardly knew. Seeking any human repository for their vengeance, they killed the schoolboy only because he was the first person they caught up with.

It is already customary to describe Kinsella's death as one of a surge in stabbings across Britain, and specifically on the streets of the capital. A narrative has emerged, partly the creation of Kinsella's parents, who are now leading a national campaign against knife crime, wherein the teenager's murder is a microcosm of wider social decay.

But the deeper tragedy of Kinsella's death – the utter arbitrariness of it – is a function not just of the society he lived in but, more specifically, of the territory he inhabited on that fateful, and fatal, night. The fuller explanation of his death is to be found not from the broad canvas of contemporary Britain, but from the zoomed-in purview of an urban "hood". It is one with which I'm familiar, from my time as a youth worker within it. Kinsella was killed because he was on someone else's turf, in an area of London where trespassers are rarely forgiven. He was in the wrong part of the "V".

The V springs forth just north of King's Cross, and is formed by the Caledonian Road and York Way, on whose northern cusp Kinsella was attacked. The two most visible landmarks on the horizon of those within it are Holloway prison, half a mile to the north, and Pentonville prison, on Caledonian Road itself – giant chambers of criminal intent both, in whose shadow residents of the V live. The area has no coherent or official name (unlike Somerstown to the west).

The Caledonian Road (or "Cally", as it is locally known) was so named because of its Victorian status as a refuge to poor children. Formerly known as Chalk Road, the road was renamed after the building of the Royal Caledonian Asylum in 1828. That asylum was designed to house the children of impoverished and exiled Scots. The Cally runs north from that other Victorian monument, King's Cross, and forms the eastern boundary of the V. Sandwiched between the Cally and York Way, a desolate landscape unfolds. Within the V are back-to-back estates that envelop their residents in a sequence of tower blocks, separated by roads whose inaccessibility makes them very much the residents' own.

By the end of each school day, these streets are populated almost exclusively by children. In appearance they are the feral youth of tabloid stereotype: attired with dirty sportswear, the boys parking their oversize bikes, and the girls mixing with them in packs of up to a dozen or more. Many of them smoke or drink; on some the acrid stench of cannabis is overwhelming, and with it comes that bipolar flittering between insouciance and paranoia which is the mark of regular skunk use. Drugs are a huge problem in the area; police have tried to clamp down on heroin and cocaine dealers in particular, but it's rare that you'll find a teenager here who, even if he doesn't take any drugs himself, doesn't know a dealer several stages removed from the bottom of the chain.

In the very bowels of the V, the centre of its centre, sits a playground around whose concrete innards many of the children congregate in the afternoon and at night. It runs adjacent to a patch of land known as Crumbles Castle. Local myth says the name comes from the manner in which residents rebuilt the surrounding area from crumbs after the war; in fact it emerged as a reference to the scattered concrete and debris that litter the area. Like the poor Scots that preceded them, the children here have no affluence to boast of. Many are from families where nobody has worked for several generations, and very few have two parents.

This last point explains, to some extent at least, the role played in the area by Richard Frankland. Known locally as "Beef", he derides the popular caricatures of these youngsters as inaccurate and inhumane. Beef, 42, runs Prospex, a youth charity whose aim is "turning young lives around", and for which I volunteer as part of a street team. Beef was given his nickname by a teacher at junior school: in consecutive days Frankland – children were called by their surnames back then – moved from Frankfurter to Beefburger to Beef, which stuck.

At 6ft 2in and with an unorthodox (and, frankly, intimidating) hairstyle, his is an imposing handshake the first time you meet him. Beef, a married father of two girls, left school at 16 and, a decade in carpentry aside, has spent his working life with young people. He spent years as youth pastor in Morden Baptist Church, and sees this as his calling.

But it becomes clear, within minutes of walking through the estates with him, as volunteers on the "street teams" do, that in a very fundamental sense Beef is a father to this fractured community. Modesty forbids him from admitting it, but what he represents to these children, and what he exudes in person, is the authority they lack at home.

"You try to be a positive role model, because that's what these guys don't have," he says. "My starting point is that these young people are basically good people who haven't chosen to live such tough lives. They've grown up knowing life on the street, and maybe haven't been given the ' chance to engage with people who show them respect. A lot of the parents are struggling very hard on low incomes; it's not an easy place to raise children." His guiding dictum towards young people is "be sympathetic, not scared".

On the day that we meet to discuss this article, Beef snaps his finger to remind himself that he must go down the road to re-hang a radiator for a single mother whose son he knows. "Really, it's about being there to meet the young people's needs," he says. "Sometimes they'll ask you to write a letter if they're going to court, or give them a reference, or stand up to a teacher in school." Prospex runs several different schemes to help young people with their personal development, from local projects in the community and family support to literacy and numeracy (more than 90 per cent of those aged 11 or over with whom Prospex works are not in school or training). A few of the luckier young people are given the chance to go on trips – mountain climbing in Wales to learn that no mountain is too high to climb, for example – opening new horizons to young people who very rarely get outside of north London.

To anyone even vaguely familiar with Beef's enduring influence, and the impact of what Prospex does, it is inconceivable that the area could survive without him. The relationships his team forge are the glue of the V. Street teams prevent stabbings or cool off heated situations on a weekly basis – usually because of Beef's presence. That gives him an almost inexhaustible authority when telling them to put their weapons away, stop drinking of an evening, or be nicer to their mums than they were the previous week.

And yet funding is fragile; the tiny team of four full-time staff at Prospex depends largely on local benefactors, and in a recession both they and big corporations zip up their wallets. Forced out of their highly visible office on the Cally because of unaffordable rent costs, the team are now ensconced inside one of the estates in which they work. The new office has its advantages, but is cramped.

Street teams such as mine, usually composed of Beef plus a volunteer, don jackets emblazoned with the Prospex logo and patrol the area on weekday nights. Our aims are twofold: first, to intervene if we see trouble brewing; and second, to assert a highly visible adult presence in the area. The second dominates the first, but despite the presence of Beef, both are terrifying to begin with, and never without anxiety.

I remember the first time I approached Crumbles Castle. Around 30 children were congregated in groups of six or seven. Several were openly smoking spliffs; two showed me the bag of weed they'd just invested in. Intrigued by the presence of a little Indian figure next to the more familiar Beef, they enquired as to the origins of my gold-framed watch, and asked to see it. Then two promptly lunged for it. It took some getting back.

At other times, it's a question of cooling off heat. Somebody knows someone whose brother was bottled that night: they've told their mate from the next estate who is coming down to settle it. Here, there are advantages in breaking groups up, and preaching the mantra of boundaries-and-consequences. There are some things, you say, that are just plain wrong, out of order, unacceptable. There are boundaries: someone getting bottled is wrong, but so is revenge. And, you say, not only is it wrong, it'll cost you: if you don't stop drinking and go home, we'll think very hard about whether you can come on our next hiking trip to Wales.

In dimly lit streets, these conversations can be difficult to have. Mostly, my first concern, and that of all street workers, is just to get an audience. This is difficult if the young people are distracted (easily done when stoned, or in the presence of the other sex), if they don't take you seriously, or if they hardly know you. They think to themselves: what can he do for me? If conversation is all you've got, it has to be good – which means it has to be relevant. It's only after several weeks on the beat, when the young people are beginning to recognise you and offer a bumped fist (a "spud") as a hello, that you can expect to get a hearing. It's then, in those slippery moments of recognition, that your own reward and satisfaction accrues.

The constant difficulty resides in the fact that, as an adult wearing the Prospex logo, you are required to represent authority – in other words, law-abiding decency and general virtue. This imposes huge restrictions on behaviour – I, like Beef, make sure I'm never seen smoking or drinking in the V – but it also inhibits conversation. There is an impulse to be matey, to talk in a different lingo, to share your memories of getting stoned as a teenager. But, throughout, you have to encourage more effort with schoolwork, and less effort on the wrong side of the law. It's not easy being a paragon of virtue if virtue is not what they're into.

Beef and Prospex have patrolled this area for eight years. They, more than the police, have earned the trust of the community, and understand its tensions. "All the statistics say that the Cally is meant to be a safe area. The trouble is you have a lot of different groups here vying for power," says Beef. The words he uses to describe the V are "void" and "vortex". "It's a power void. There's no one group [he avoids "gangs", thinking it unhelpful] of young people in charge. Each little group is trying to show they're a serious bunch. And lots of different people from the surrounding areas are sucked into it..." Like a vortex? "Exactly, a vortex." On the night that he was celebrating his GCSEs at a local bar called Shillibeers, Ben Kinsella, who lived half-a-mile east of the V and closer to Highbury, was sucked into that vortex.

For years, the area has been a battlefield between two families in particular: the Riley's and the Adams', with the latter lately considered supreme. Terry Adams, head of the clan, was Britain's most feared gangster when he led the infamous Clerkenwell Crime Syndicate, also known as the A Team. Once worth an estimated £11m, he was jailed in 2007 for laundering £1m.

Police confirmed last week that a member of the Adams family has professed anger at the death of a young man (Kinsella) on their turf. In secret recordings made by police, Braithwaite, one of Kinsella's killers, told his accomplices that there was a bounty on his head. "The family have got big money down," he said. "They have put money on whoever was involved... the Adams family's right-hand man wants to speak to me."

It's not clear to police why the Adams family should be so distressed at the actions of murderers police describe as formerly "low-level" drug dealers. But one theory among senior police is a desire to reassert authority in an area where old tribal allegiances have been fractured by the operations of small-timers from surrounding areas, such as Kinsella's killers. In other words, to lay down the law anew at the top of the V. "It's tense just now. There's a lot of heat and frustration around, and we're hearing a lot about events where we don't know if they're random or connected," Beef says. In the year since Kinsella died, tensions have mounted. A few weeks ago there were three stabbings near a petrol station at its bottom tip.

Superintendent John Sutherland of Islington arrived in the borough six months before Kinsella's death. Two factors, he says, distinguish violent crimes here. First, "the reason for violence seems far more trivial now: it does seem to require minimal provocation". And second: "you can go very quickly from 0 to 60" – that is, from a spilled pint or an expression of disrespect to a chillingly brutal murder.

Such is the randomness of Kinsella's involvement in the lives of his murderers. Braithwaite, 20, was a local troublemaker and small-time dealer; Kika and Alleyne were also familiar faces. All had previous convictions in and around the area. All were small-timers who saw the V as somewhere to display their wares.

Between the overlord Adams and the underling dealers, Kinsella was, and after death continues to be, caught in tribal warfare that had little to do with him. In the coming battle for the soul of this area, Ben Kinsella's legacy will be determined by whether the void continues to draw vulnerable young people into it, or whether the stamina of Beef and Prospex prevails.