The journey to the gleaming new Shadwell Sure Start children’s centre runs through some of the poorest parts of London, past gritty council tower blocks, along grey concrete estates and dingy patches of grass. Inside the centre, though, with its windows spattered with cheerful orange dots, it is light and bright, full of enticing toys, squashy cushions and foam furniture in primary colours. In the undertwos’ nursery (open for a 10½hour day, from 7.30am to 6pm) three placid toddlers sit having tea spooned into their mouths by as many staff.

In her small office is Meena Hoque, clad in a turquoise sari, who has run Sure Start’s preschool education and family projects in this part of the East End for several years. She is explaining that the people who flock to her centre’s doors are the middle-class and wealthy of nearby Wapping, “nannies in four by fours” and the mums and dads of double-earning families. They come for the free baby yoga and massage classes, the toy library, the play sessions, the breast-feeding and weaning workshops, the parenting classes, the nursery rhyme sessions – although probably not to use the centre’s prayer room.

The people who are not queueing up are the very people who Sure Start programmes, now being launched in thousands of new children’s centres across the country, were set up to reach: the most vulnerable and at risk, or the ones who are depressed and sitting their youngsters in front of the telly day in, day out. Maybe they are worried that the staff will judge them. Maybe they don’t rate baby yoga and breast-feeding lessons. Maybe they are being put off by the yummy mummies.

Labour’s ambitious schemes to reach out to the poorest children in Britain and reduce the chances of them ending up unemployed, abused or in jail have cost billions since it came to power in 1997. According to one insider, the idea behind the initial Sure Start programmes was Treasury-led: if toddlers at risk of becoming criminals, junkies or simply jobless could be bombarded with all the benefits that middle-class mummies provided as a matter of course – from picture books to trips to art galleries – then, the thinking went, their children might grow up to excel at school and become “tax generators rather than tax consumers”.

Since Sure Start was launched in the late 1990s the experts have grown increasingly sceptical. Last week a Durham University study found that despite the £21 billion poured into preschool education and other similar initiatives since 2001, the cognitive abilities of 35,000 four and five-year-olds have not risen since then, nor has the gap in achievement narrowed between children from poorer families and those from affluent ones. “I would have hoped that this would have closed the gap between disadvantaged and advantaged kids in attainment,” said Christine Merrell of Durham University.

The research has fanned the flames of what is fast becoming a complex and fierce debate. On the one side are increasingly sceptical experts who argue that Sure Start programmes could turn out to be a massive waste of money: not least because they were not tested and piloted in small-scale studies before being launched nationwide. Later this year Professor Michael Rutter, one of our leading child psychiatrists, will contribute to a book criticising the government on just these grounds.

On the other side are mothers, and not just middle-class ones, who say that all these classes for their babies and toddlers, the chance to mix and mingle with other local parents at a life-changing time, is immeasurably valuable and it’s too early to judge whether we are getting our money’s worth.

Tania White, an “independent, totally secure middle-class mum” from north London, was given a Sure Start card entitling her to free access to all manner of classes when her son was born two years ago; she took him to The Buttercups, a toddler and parent playgroup. For the first time in seven years of living in the neighbourhood she felt part of the community, she says, and even attended a class held on a nearby council estate: “I met lots of different kinds of mums and felt bonded by the experience of motherhood. Now if there was a knifing or something horrible like that locally I would hope that we might all get together.”

However, Jay Belsky, the American psychology professor who is one of the directors of a £20m research programme into the earliest versions of Sure Start (which were based around deprived neighbourhoods and have since been abandoned) says the team found few overall advantages for 8,000 babies growing up in Sure Start areas at nine months old. Even more worryingly, the three-year-olds of teenage mums did better in areas that were not receiving the Sure Start programmes.

“There were three core hopes for how children might be affected,” says Belsky, now director of the Institute for the Study of Children, Families and Social Issues at Birkbeck College, London. “They would get access directly to services like speech therapy and book programmes; the parenting of the children would be improved and communities would be brought closer together and made safer.”

He thinks the most likely reason for the team’s findings is that “the more middle-class families took advantage of these programmes and gobbled up the resources. The most disadvantaged families did not feel comfortable coming in. The workers did not go out and knock on the doors of the poor families because they were busy with the demands of the middle-class families.”

The team revisited the 8,000 children when they were aged three and again at age five. The results of that research – as yet unpublished – will be given to the government before the end of the year.

Are ministers listening to the experts or siding with the mums? Well, they have abandoned the earliest 500 neighbourhood-based Sure Start schemes. But last month they announced £4 billion more to be spent over the next three years, including launching nationwide a “universal programme” of 3,500 Sure Start children’s centres by 2010, many of which will include a day nursery for preschool children to make it easier for their mothers to go out to work.

Sure Start centres will become “a permanent part of the modern welfare state”, says Beverley Hughes, the children’s minister, who also insists that there is independent research showing that “two years of high-quality early education can give children a four to six-month advantage at entry to reception class – and help those from poorer backgrounds to catch up”.

Belsky says Sure Start was loosely based on “work in the US that showed that well targeted programmes either involving quality childcare or home visiting or both could work and that early intervention could benefit the most vulnerable children in the long term”. Decades after 50 poor black children went through the High/Scope nursery programme in America, it was shown that the state had saved $250,000 on each child compared with what had to be spent on crime, school and welfare follow-up for a similar 50 children who had not gone through the programme.

However, the government, says Belsky, “exaggerated what the US work found. They said early intervention does work when in fact it only could work”.

Belsky defends ministers’ decision to press ahead even though the jury is out on whether or not the scheme will reap dividends: “We may look back and say Sure Start was too grand and expensive but you could argue that a big hole in the wall had to be blown open. They had to get the notion accepted that you must spend money to improve the lot of the most disadvantaged families and children. Now even the Tories are saying we should be spending lots of money on the poorest and the youngest children.

“The real proof in the pudding is whether or not this major investment will be recouped in 10 to 20 years’ time. If we reduce the number of children who go to school not ready to learn, not emotionally secure, not able to sit still or play or listen to instructions; if we turn out parents capable of managing their children’s behaviour, of not neglecting them or being abusive, then I think we will be able to say it was worth it.”

But will we?

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