Daniel Jeffreys finds out how, in barely two years, a new mayor has reclaimed the streets of one of America's most dangerous cities
Last month the Metropolitan Police were here, riding around Harlem with the NYPD Task Force. In August officials from the Home Office paid a visit to the Bronx. Next month the Met will be back again, to study weapons control. In the past year more than 10 MPs have spent time in what was a world-class crime zone.

During 1990 there were 2,245 murders in New York City, an average of six a day. In 1995 there were fewer than 1,200 for the first time since 1973, when the city was only three-quarters of its current size. Last year New York didn't even make the top 100 of America's most dangerous cities. The trend looks sustainable. In the two-year period since 1993 every New York precinct has seen a double-digit decline in the overall crime rate - and that hasn't happened since the Second World War.

"I can't call it a miracle," says Rudy Giuliani, the combative Mayor of New York. "That would be tempting fate. What we have is a stunning reward for hard work."

New York's success has been so striking that more than 30 big cities world-wide have sent delegations on study tours. This month there will be visits from South Africa and Canada. The British visits suggest that British politicians think they can reproduce New York's revolution.

In 1990 New Yorkers had a bunker mentality. All categories of crime were growing among headline atrocities, such as the multiple murders at the Happy Land Social Club. The mayor at that time, David Dinkins, was under siege: "Do something Dave," read the front page of the New York Post.

Dinkins did, although he acted too late to save his political hide. With some money from the federal government the Dinkins administration hired 7,000 extra police officers, a 12 per cent increase in the NYPD roster. On election day in 1993 the new mayor, Giuliani, had the necessary troops for a revolutionary approach to crime.

Giuliani campaigned on a law-and-order ticket. In his speeches he attacked what he called "quality-of-life crimes". These included aggressive begging and graffiti, offences that had been largely tolerated by the NYPD, along with unlicensed street trading and small-time drugs dealing. When Giuliani was elected most New Yorkers thought petty crimes were an inevitable part of life. Now that crime is falling so sharply, it's no wonder his staff are rushing to take the credit.

"New York was known as a city out of control," says Lenny Alcivar, a senior adviser in the Giuliani administration. "Minor crimes were tolerated because the police were supposed to concentrate on major crimes. That was a mistake. The policy of tolerance was the force behind the rise in major crime."

The new strategy is radically different. "The NYPD now comes down hard on nuisance crimes," says Alcivar. "We have a message: you will no longer harass people by begging for money, you will not sell drugs on street corners, you will not spray graffiti. This year 135 cities have worse crime records than New York. We believe that if you aggressively pursue the small crimes, the larger problems will take care of themselves."

It sounds glib but the strategy has worked, according to experts such as Lawrence Sherman, a professor of criminology at the University of Maryland. "Since the Sixties, social scientists have been telling police that they can't really prevent crime because its root causes are beyond their grasp," he says. "Giuliani has led a revolution against that dogma and proved just the opposite. The result is that a lot of police departments are scrambling to copy New York's tactics."

"The catchphrase is 'zero tolerance'," says Jack Maple, the deputy commissioner of the NYPD and the man many call the guru of New York's revolution. He offers an example. "Last week an officer stopped a motorcyclist just for not wearing a helmet. Who would think that could happen in New York? He arrested the guy after he found two handguns, then a search of his apartment uncovered an arsenal of weapons." That's guns off the street, another key part of the Giuliani strategy. "Relentless follow-up investigation is the key to driving down crime. You take all the pearls and string them together."

The analogy refers to Giuliani's belief that a relatively small number of people commit most crimes, and that they are loosely affiliated or come into contact with one another buying guns or drugs, or selling stolen goods. Accept that and the rest is simple. With good detective work, one arrest should lead to another. It also means that New Yorkers are getting used to a stop-and-search mentality, with much wider interpretations of the "probable cause" required to frisk a subject.

At police headquarters Maple pursues this policy with ruthless determination. From his hi-tech "war room" he has pioneered the use of "computer-generated statistics" (Comstat) to find and eliminate criminal hot spots. Twice a week he holds a Comstat meeting for New York's eight police commanders, where they study the latest crime figures in minute detail.

"If an area shows an increase in activity, we immediately respond with a show of force," says Maple. He believes urban policing should be run like a military campaign, with mobile units of officers available for deployment anywhere in the city. "We have taken back New York block by block, and we'll defend it using the same principles."

The Comstat meetings are also shock therapy for the NYPD commanders, who must come to the table with specific plans to cope with problems in their part of the city. "No one is in trouble if crime is up," says Maple. "They're in trouble if they don't have some type of plan to knock it down."

Comstat meetings fit well with other parts of the strategy. Mayor Giuliani has made the police more visible, his task-force has removed thousands of guns from the streets, and police corruption has been sharply reduced.

"Corrupt cops were a key problem," says Alcivar. "The toleration of minor crimes produced corruption which then fed back to the streets, encouraging other illegal activity. If an officer can ignore a drug deal, he can also benefit from it. That's no longer possible and community confidence in the NYPD is rising again."

At 11pm on a Friday night all these strategies are at work in the same squad car where Manhattan North task-force officers McGrouther and Porrazzo are going over their Comstat notes. "The blocks between 135th and 137th streets got six complaints from the community last week," says McGrouther. "All related to drug deals."

"We'll take more trips along there tonight," says Porrazzo.

After a few minutes the steady chatter on their police radio becomes more urgent. "A gun seen at the corner of 136 and Broadway," says a dispatcher as Porrazzo accelerates, siren blaring.

By the time we arrive there are five police vehicles at the scene and others are on the way. It's a small crime by past New York standards but the response is impressive and highly visible. Spectators can see that the police are serious. The two youths pressed against the wall in handcuffs will spend the weekend on Riker's Island, one of America's toughest prisons. It's also another gun off the street.

Throughout the evening McGrouther and Porrazzo follow the same drill and have no doubt that it's working. "It's so much quieter here now," says Porrazzo. "You can feel the change. You see a lot more people on the street, just relaxing. We feel in control."

That is reflected in the rest of the city. New Yorkers are going out in neighbourhoods once thought unsafe, people talk more to each other and tourism is rising at more than 10 per cent a year. At a recent press conference to announce another drop in crime, Mayor Giuliani brought the New York director of tourism with him. "We are going to use these crime figures," says Steven Morello, who runs the New York Visitors Bureau. "They will be prominent in our marketing efforts."

There have been problems with the Giuliani plan. Complaints about police brutality are up by 24 per cent on a year ago. Homeless people say they have been forced into shelters, where there is more violence and disease. Community representatives in some parts of the city say the police have become over-zealous. "We are working on this," says police commissioner William Bratton. "The culprits in these cases are the officers involved, not the policies. The bad officers will go, the policies will stay."

Critics of the New York plan say the city has been lucky. After the Eighties crime wave many criminals are now in jail. The number of New Yorkers aged 19 to 25 is below average just now, and this group has the highest crime rate. Crack use is declining and there are more people in the police force.

"The pendulum could easily swing back," says James Fox, a professor of Criminal Justice at Northeastern University. "When current inmates leave prison and the 19- to 25-year-old group bulges again in about five years, then we can test the Giuliani theory."

The mayor says he's ready, and opinion polls show the city supports his uncompromising aggression. Arrests for misdemeanours that include most "quality of life" crimes have risen by 73 per cent since 1994, and the latest New York Times poll shows that 76 per cent of city residents think Giuliani is doing a good job controlling crime. That's some correlation.

Not that New York is safe. Ask the relatives of Maria Carrasquillo, who was gunned down with her two sons while shopping for shoes. She was one of six victims of a schizophrenic with a handgun who got upset over a pair of sneakers four days before Christmas.

"That kind of random crime is tragic," says Maple. "It's the hardest to control, but our plan is helping to eliminate illegal weapons and that will keep guns away from psychopaths."

Does Maple think the Giuliani project can work in other cities, such as London? "Most definitely, because it's so simple," he says. "If you refuse to tolerate any kind of crime, the numbers for serious crime will begin to go down. By contrast, if you tolerate graffiti, the culprit soon moves on to worse acts. Before you know it, he has a knife, then a gun, and he's lost all respect for the police."

The exercise is not cheap. The NYPD budget is rising at 6 per cent a year, while other parts of city government see cuts. Despite that, Britain cannot afford to ignore New York's experience. A 40 per cent drop in homicides and assaults does not happen by accident, and as New Yorkers grow confident in their new security they've started to be nicer to each other. Now that's an achievement worth copying.