How can we let children live in fear? As soon as we saw the gun, we knew what was going to happen. We all leant forward, hundreds of us watching the flickering film, and all around me in the school in east London I could see the anxious faces of the children. Some of them were averting their eyes, or staring through splayed fingers; and then - Bang! - came the inevitable shot, and a gasp went up from the audience as the life of another child began to leak away, like the lives of the 21 teenagers who have died in London this year, shot or stabbed at the hands of other teenagers. And then it was the climax of the show, and a hip-hop group called Green Jade came on, and started singing a very catchy number all about what it was like to be caught in the crossfire. It was called Brah-kah-kah, and on the instructions of Wizdom, the lead singer, we all started waving peace signs in the air. It would be an exaggeration to say that I understood every word of the lyrics. But I certainly understood the chorus, and I can still hear it in my head. "Brah-ka-kah", sang Wizdom, ducking and weaving his body like a man dodging bullets, and I looked at the singers making their Eminem gestures, flicking their fingers as though trying to rid them of a particularly irritating piece of Sellotape. I looked at the sign on the stage behind them, proclaiming that the project was called Gunz Down; and then I looked out again at that sea of rapt and innocent faces. And I had a flashback, and I remembered when I used to sit, just like these 11- to 13-year-olds, in the morning assembly of my inner-London school, and like them we all squatted in rows, cross-legged, and like them we chorused obediently at whatever the head teacher said. But I tell you something, folks. When we had morning assembly at my ILEA school in 1970s' Camden, we didn't have songs like Brah-kah-kah, all about what happens when someone starts firing a sub-machine gun - and nor, I bet, did any other pupils across the Greater London area. We had All Things Bright and Beautiful by Mrs C F Alexander and Morning Has Broken by Cat Stevens. We didn't have people imploring us not to shoot each other. At the very most we were urged not to take sweets from strangers; and as I thought about my childhood, and the childhood of these children today, I realised how much had changed; and on behalf of my entire fortysomething generation, I had a spasm of collective guilt that we have managed to create a society so alarming that it seems quite normal for morning assembly to consist of an hour of sketches, homilies and songs about the dangers of guns. Worse still, you only have to talk to the head teacher, and to the police, to realise that the risk to some of these children is real, and terrifying. In some parts of the city, there are schoolchildren facing daily acts of violence. Bicycles are stolen. Mobile phones are stolen. The other day, a pupil at this school was beaten up for just crossing the road, because he had strayed from one post code to another. There have been two recent killings in the immediate vicinity of the school, and, though the school itself is safe, the warfare goes on outside - and it fills the rest of us, the bourgeois public of London - with an awful mixture of paranoia and indifference. We know about the hair-raising names of some of these 257 London gangs, such as KDM (for Kill Dem Pussies); and we scuttle ever more fearfully through certain areas. The public has become more alarmed about the risk of gun and knife crime, with 56 per cent believing that it has increased in their neighbourhood in the past five years; and yet we have also become desensitised to the horror, and every new stabbing or shooting seems somehow to slip lower and lower on the news agenda - to the point where murders of children, taking place a mile and a half from Westminster, have become as banal as a bus crash in some far-off country. We have read enough to become experts on the causes of the problem: the absence of parental control, the shortage of male role models. We know that the children are themselves afraid - afraid of failing to conform. We know that the gang has itself become a kind of sanctuary, where children can find affirmation and esteem and respect, even for doing terrible things; and yet we are failing to take the kind of urgent practical steps needed to address the root causes. We can do more to intercept guns, and we can have yet another crackdown on knives; but we can pass all the laws we like, and we can sweep every Kitchen Devil from the supermarket shelves, and we will not deal with the fundamental problem that, as long as children feel safer with a knife in their pocket, they will get hold of that knife. That's why I believe in the work of people such as Wizdom and Patrick Regan of Gunz Down. There was a brilliant passage in the show, in which Wizdom and a colleague acted out a classic flashpoint between two youths, over a £20 debt, and showed the children how to draw back from the brink of anger; and you could see the way it struck home. But a show such as Gunz Down takes time, and commitment, and money. The school paid £300 to have them, and yet it cost the group £2,000 to put it on. It would be tragic if good organisations such as this were not funded, just because some of its members are Christian in their inspiration, and when there was not a word of Bible-bashing or preaching from any of them. It would be tragic, because these organisations are helping to tackle the emotions behind the attacks and the killings. It's not the guns and the knives that are killing young people. It's the yawning lack of boundaries; it's the yearning for the wrong kind of respect, and above all it is fear.