It is 10.30 on a chilly term-time Wednesday morning, and the streets of Wood Green are fairly empty. Pensioners and pram-pushing parents battle against the wind, oblivious to two police officers, one educational welfare officer and one youth worker who are cruising the streets, eyes peeled.

Two days after the police’s new truancy powers came into force, I have joined PC Andy Briers and his team in the north London borough of Haringey, where absenteeism from school stands at almost twice the national average. Police here have launched a “truancy patrol”, working with education welfare and social services, touring the streets of the borough in a local authority van.

Nosey neighbours and off-duty-teachers used to be the only spies on the street as far as truants were concerned. But now there is a new spotlight directed on them, and it’s coming straight from Westminster. Reducing truancy has a new, high profile which is linked to several Government policies - pushing up standards, reducing unauthorised absence and cutting crime. By the year 2002 Labour is pledged to have cut school absenteeism by one-third.

On the front line, the police have been empowered to take truants back to school. In the past they needed evidence that children were at significant risk of harm before they could pick them up - standing around in a rent-boy area, for instance, or sniffing glue by a canal. But under section 16 of the new Crime and Disorder Act, they can pick up children they believe are absent without authority and take them back to school.

Our van passes a wan-looking boy, sitting dejected on the pavement, his bike flung beside him. PC Briers brings the van to an abrupt halt. Welfare officer Nora Wellbelove and youth worker Beauty Bozui jump out and talk to the boy, who says he was on his way to a pupil referral unit two miles away.

He is alarmingly pale and very thin. He complains of a stomach ache. While Ms Wellbelove feels his forehead, PC Briers lifts the beaten-up bike into the back of the van. “You were lucky we were passing,” says Ms Wellbelove, trying to cheer him up. “Have you had these pains before? Have you had any breakfast?” It is unclear whether this13-year-old is playing truant, was on his way to school, or ought to be at home in bed. Nevertheless, he is delivered into the hands of his personal tutor at the pupil referrral unit where he is attending key stage 3 classes. It has emerged en route that he is living with his father and has to travel six miles to get there.

Back in the van, PC Briers, aformer English teacher and now part of the youth and community section of Muswell Hill police station, scans the chip shops for juvenile miscreants. A teenage girl is walking along with a dummy in her mouth (fashionable, apparently). When she is questioned, she says she too is on her way to the unit.

Briers then spots another young woman in a heavily disguised school uniform and leaps out to talk to her, taking his notebook from under his cap. She produces a suspiciously dog-eared note excusing her from school on the grounds of a doctor’s appointment. Then she confesses she’s already on report for truancy.

Andy Briers has a friendly manner and doesn’t seem to offend the young people he questions. “It’s a commonsense approach,” he says. “As long as we can ascertain who the child is and what school he or she attends, it will be followed up by education welfare. There’s no point in upsetting anybody, or causing problems.”

The new powers are useful in giving police an authoritative edge when it comes to persuading some children to return to school, but are unlikely to be used to place refuseniks under arrest. “It’s not a question of bundling people into the van,” says PC Richard Mansfield, the other officer on the patrol. “It’s a question of using discretion.”

Depressingly, many of the children on the street genuinely have nowhere else to be. Two girls on bicycles outside the grounds of Tottenham Hotspur turn out to be refugees recently-arrived from Mozambique and still without school places.

A boy apprehended outside a second-hand fridge shop tells the constables he is permanently excluded from his primary school. A minute into the conversation, his older brother materialises and instructs the boy in angry tones to “talk up now. What were you excluded for?” A convoluted story about a stolen key emerges, but what is clear is that no alternative provision has been arranged. Wellbelove gives the older brother the phone number of education welfare.

The patrol has its farcical element. At one point, several of the team set off at a run down Tottenham High Road, trying to catch up with a young woman who turns out to be 17 and on her way to work. A boy questioned at a bus stop says he’s just had a check-up with the orthodontist. Briers’ light-hearted questioning makes him smile, and his mouth opens to reveal a huge brace across his teeth.

The Government has made clear the importance it attaches to school attendance by placing the remit to “make a step-change in the scale of truancy and exclusions from school” in the hands of the Social Exclusion Unit. But truancy is a many-headed beast with multiple causes and complex forms. Parents are the first line of defence against it, but up to half of the children who stay away from school are thought to do so with the connivance of their parents, according to a recent report on truancy and exclusion by the Social Exclusion Unit.

Some parents use their children to help with shopping or care of younger siblings. A pre-Christmas sweep through street markets in the neighbouring borough of Islington found large numbers of primary children out shopping with their parents in school time.

Other truants are motivated more by dread of school than the lure of the streets, which appears to be one explanation for the wide variation in truancy levels between apparently similar schools. OFSTED has found that secondary school pupils who are weak readers are relatively likely to play truant, as are pupils behind with GCSE coursework and victims of bullying. Overall, truants tend to be older pupils from poorer backgrounds.

From next autumn, schools and LEAs will be required to set targets for truancy reduction. But the report from the Social Exclusion Unit makes clear the Government’s own difficulty in gauging the extent of the problem. “Official figures show relatively low and stable levels of truancy,” it says. “But according to surveys of young people, the levels are far higher. The twice-daily registrations carried out by schools fail to capture the extent to which truancy is the norm for many children.”

The report authors go on to quote a major study which found that nearly one in 10 15-year-olds played truant at least once a week. “The study had an 83 per cent response rate,” they comment. “It is likely that many of those who did not respond were truanting at the time of the survey.”