IT WAS hot in Brixton on Tuesday night. Hot enough to barbecue chicken on the Tarmac. Down the grey street where John Major was brought up, gangs of boys leant against open-topped jeeps and talked into mobile phones in an impenetrable patois. Sleek cars cruised lazily up the road, windows wound down, music booming forth, plastic spoilers rattling to the beat.

Jah Screechy walked through the heat haze, cool as an ice-box. A man leant from a passing car and shouted, 'Yo, Screech'. Screechy nodded without breaking stride. He was carrying the hand baggage of the successful Brixtonian: cell phone, a briefcase-sized appointments book and a leather case containing spare phone batteries. If he had brought his car, he would, he explained, also have been carrying his pull-out stereo system.

'Don't trust Brixton, it's full of criminals,' he said, sucking through his teeth in exasperation. 'When you see someone with a mobile phone round here it's a drugs phone, know what I'm saying. Me, I carry mine because I'm a musician, officer.'

By night, between phone calls - to his producer, to his manager, to his friend who it transpired had taken his mobile to the fairground ('I can't hear, call me when he gets off the dodgems') - Jah Screechy makes music. He is a toast master, a rap artist, a favourite of the young black Britons who like ragga music. His style is to talk at impressive speed along to reggae tunes, which are then remixed in a manner called, according to his producer, Curtis, 'Jungle Techno, but the name changes every six months'. Last year Screechy spent a couple of weeks at number two in the national charts, with a song called 'On a Ragga Trip'. He appeared on Top of the Pops. Now he can't go to a party without someone handing him a microphone and asking him to say a few rhyming, rhythmical words.

Despite the success, however, Screechy hasn't given up his day job. By day he switches off the mobile and travels the streets of south London in a position inaccessible even to the most determined of pubescents. He is a bus driver, steering the 137 from Brixton garage to Oxford Circus and back again.

'They call me the singing bus driver,' he said. 'I used to be on the one-mans. But the schoolkids gave me grief and I didn't like dealing with the public. So now I've got a conductor to do that, and I can sit in my cab and think of lyrics.'

Appropriately for a bus driver, his lyrical inspiration tends to arrive in batches: sometimes he doesn't compose a rap for ages and then, suddenly, three come to him at once. At the moment, he says, he is in a productive period.

'I can't stop the chat, man. Because of what's going on around me.'

His lyrics are drawn from real life, from the ragga scene. Ragga is almost exclusively a black enthusiasm. It has given an identity to second- and third-generation black Britons who feel no desire to assimilate into the mainstream: raggamuffins pepper their talk with thick Jamaican slang, even if their parents were born in Birmingham. The outsider's view of ragga culture is tainted by gun fights at concerts, rappers with lewd and anti-police lyrics, girls dancing provocatively in leggings pulled up under their armpits.

Oddly, this was not a view that Jah Screechy totally disagreed with.

'Things have gone downhill,' he said as he settled into a smart Brixton bar with a bottle of Kenyan lager. 'It worries me. When I first started in 1981 you could go to a dance and it was nice, you know. Nice people went. Now, it's guns and madness. Only bad boys go to dances. Nice people, they have private parties. And the people who are doing this, they are spoiling it for themselves. Not many clubs will host black dances any more. And who can blame them? I mean people don't fire guns at Elton John concerts.'

This is on Screechy's mind as he drives through London's traffic, or records a potential hit in his make-shift studio in a community centre. He believes he has a mission to change things.

'I am like a preacher,' he said. 'When I chat I want people to learn. Sure I can do slack lyrics about guns and girls, it's easy, but I won't. I prefer to do cultural lyrics, that will put people in touch with their culture. And I want to chat about peace.'

He claims that rappers who spout about women or encourage dance-goers to pull out their guns are taking the easy way out, and must bear a measure of the blame for the decline of the dance.

'It's easy to get a response from the crowd with slackness. It's harder to get them going, get them listening and enjoying, with cultural lyrics. But I can do it. I done a gig at the Ritzy, Streatham, for under-18s. They loved me, grabbed hold of me, tearing off my tracksuit. It was nice, but it was frightening. Young kids, man, 13-year-old girls giving me their phone numbers. I mean, what am I gonna do with them?'

As he spoke, a police siren wailed in the distance. Did Screechy think Brixton would erupt this summer as it has in the past?

'I've had my fill of police, don't get me wrong,' he said. 'But they have a job to do. Drugs and guns and things, they've got to be sorted. The nice people realise that. So I don't think there's as much general tension down here now. It's more open, people mix more. Brixton's full of criminals, but there's lots of nice people, who live for the music. My music.'

His phone chirruped.

'OK, man, I'm on my way,' he answered.

He had to go, he explained, for a meeting with a man who wanted him to do a favour. I offered to give him a lift to his home, down the road in Streatham Vale. As we reached my car, there on the pavement was a familiar puddle of glass. The car's back window had a fist-sized hole in it;

the radio had been untimely ripped from the dashboard. Screechy was distraught.

'I'm really sorry, man,' he said. 'Brixton, I'm sick of it. That's why I moved out, man. The brothers said, 'Hey, you can't leave the brothers.' But I'm sick of being tarnished by the criminal brush.'

At Brixton police station, there wasn't a policeman in sight. Three ragga kids banged impatiently on the counter seeking attention. Eventually the station officer emerged with the sort of apologetic tone that must have been learnt on a how-to-deal-with-the-public course.

'I'm sorry to keep you waiting, gentlemen,' she said. 'Your friend will be out in a moment.'

Indeed, a minute later another youth appeared from the bowels of the station. 'That's the third time this week I been picked up, man,' he said to his friends.

After the group had left, muttering darkly, I gave my details to the officer. Behind her, another policewoman carried a plastic evidence bag, marked with a little label. Inside it was a revolver. Did the police worry that Brixton might go off again in the heat?

'Oh, no,' said the polite station officer. 'They're too busy breaking into cars.'

(Photograph omitted)