THE rivalry between Yardie gangs may have erupted yet again with yesterday's drive-by shooting in Walworth, South London.

Police were yesterday keeping an open mind on the motive for this latest shooting, of a 51-year-old white man, a local resident, shot twice in the head and once in the back with a sawn-off shotgun.

Neighbour Doreen Stepto said the white victim was ''a lovely family man, and very friendly''.

''I can't understand why anyone would want to shoot him,'' she said.

It follows a similar attack, also in Walworth, on the Radio 1 disc jockey, Tim Westwood, 41, who, police think, may have fallen foul of gangs battling for control of rap and hip hop clubs where DJs like him regularly appear.

In both cases the gunman - white in this instance - was on a motorbike, and that is all that currently links them.

Mr Westwood, who was injured in the arm by a gunshot while driving home from a gig in Brockwell Park, Tulse Hill, on Sunday, had apparently come up against Jamaican Yardie gangsters in the past, speaking out in his broadcasts against their activities.

He is a well respected and influential figure in the world of hip hop and rap, in spite of being white. The suggestion is that he had failed to show respect, or ''dissed'', a leading South London clubland figure.

There have been 13 killings, all apparently related to the music business and drug dealing, this year, seven in the last 11 weeks, as well as 30 shooting incidents, so it does seem that something new and dangerous has come to the streets of London.

The Westwood attack, in which his assistant, Ross Newman, also in the car, was injured, caused Shadow Home Office spokesman David Lidington to call for visitors from Jamaica, a Commonwealth country, to have to apply for visas as a means of checking criminals coming into the country. That, however, is highly unlikely to happen, and would solve nothing. The gangsters are already here, although not, it is thought, in any great number. Some estimates suggest that those waging war number only around 200.

A special intelligence-gathering unit, Operation Trident, was set up recently by the Metropolitan Police to investigate possible links between the killings and the shootings. The police response, which has been less forceful than it might have been, seems to have been affected by the criticisms of them contained in the report into the killing of Stephen Lawrence.

Among those killed were Richard Parkinson, shot dead in March at an east end club, Stratford Rex. In May, seven people were injured when two gunmen fought in another east end nightclub, Orchids in Dalston.

Gangland killings are nothing new in London, but it is the use of guns, the brazen nature of the killings, and the refusal of witnesses to talk, that is different.

I live in Brockley, a south London suburb with a substantial, well-established Caribbean population. It is quiet, leafy, not very smart, and popular with actors, because rents are low and communications good.

While it had one pub, now closed down, with a reputation for being used by drug dealers, it is no more lawless than any other part of London, and less than some, including Brixton, a few miles away, which has a huge Caribbean population, and lots of clubs and drug dealers.

In April, however, ticket agent Keith Balfour, known as ''Little Andy'' in Brixton, where his family came from, who had opened an office, Big Ballers, next door to Brockley railway station, was killed after two men walked into the premises at 1.30pm and one opened fire with a Mac-10 submachine gun, while the other kept guard at the door. The gun has not been found, nobody has been charged with his murder and the boarded-up main street office is now up for sale. Balfour, who had a criminal record, was a prominent figure in the world of club promotion and protection, or security as it is euphemistically called. He had already survived one attempted shooting and had been linked, falsely his friends claimed, in gossip about who was responsible for one of the east London killings.

His killing was particularly brazen, occurring in the early afternoon in a prominently situated office, and while he was sitting talking to his 20-year-old assistant, on her first day in the job, and a male visitor who has not come forward. Police have come up against the inevitable wall of silence.

Balfour may have brought the violent men of Brixton after him, but whoever killed him, gangland shootings simply do not happen in places like Brockley

In America, the stars of gangsta rap, which originated in Los Angeles in the late 1980s, often came from tough urban backgrounds and their songs glorify violence and the use of the gun.

They are unequivocal in their advocacy of violence.

The rapper Ice-T, for instance, who has made several films, had one hit which ran: ''I've got my 12-gauge sawed off, I'm 'bout to dust some cops off. Die, pig, die.''