The Guardian, September 99

This is the secret that everyone knows: the children of poor families are far less likely to do well in school than those whose parents are affluent. For the last ten years, this has been almost buried in denial. "Poverty is no excuse," according to the Department for Education. Neverthless, it is the key. As everyone knows.

The ministers and pundits who want to deny or diminish the link are keen to present it as the invention of soft-focus lefties trying to justify a socialist theory of education or to excuse incompetent teachers. However, the clearest and most persuasive recent evidence for the link was produced earlier this year, not by a teacher's union or a liberal academic - but by the Treasury, in its fourth report on the modernisation of Britain's tax and benefit system.

Reviewing nearly 30 years of research, the Treasury reported: "Children from disadvantaged backgrounds are much less likely to succeed in education... On 'difficult to let' estates, one in four children gain no GCSEs (the national average is one in twenty) and rates of truancy are four times the national average... There is considerable evidence that growing up in a family which has experienced financial difficulties, damages children's educational performance...

"The differences between advantaged and disadvantaged children are apparent from a very early age. At 22 months, children whose parents are in social classes one or two are already fourteen percentage points higher up the educational-development distribution than children whose parents are in social class four or five.... The data from the National Child Development Survey show that there is a strong relationship between children's performace in maths and readings tests between the ages of six and eight, and their parents' earnings, with the children of higher earning parents performing better... If one father's earnings are double the level of another, his son's maths test score is on average five percentile points higher than the other's... Going to school does not reduce the differences in early development between advantaged and disadvantaged children."

The link is strong. It is also central to the experience of Britain's schools because, as the same Treasury document confirms, poverty in Britain has trebled since 1979 to the point where a third of Britain's children - more than four million of them - now live below the poverty line. This torrent of poor children poured into the classroom at exactly the same time as standards of behaviour and achievement slumped. Our levels of pupil failure are higher than most of the rest of the developed world, but our levels of child poverty also are higher than most of the rest of the developed world. According to Eurostat, for example, 32% of children in the UK live in poor households, compared to 20% in the rest of the European Union. According to Treasury figures, we have higher poverty levels than Greece and Portugal.

The physical, emotional and social damage which is inflicted on children who live in poverty, is clearly reflected in the latest academic results. The independent group, Research and Information of State Education, trawled through Ofsted reports and matched the standards of students against the number who were claiming free school meals, the nearest available measure of poverty in the classroom. In schools with only a few poor children, one in every five pupils was scoring Grade 1; at the other end of the spectrum, in schools with a well above average number of children on free school meals, only one in a hundred was doing so.

A disadvantaged intake can make life tough for a whole school, not just for individuals. Researchers at Durham University looked at schools which have been failed and subjected to 'special measures' by Ofsted and then matched them against the six bands of disadvantage which are used by the Department of Education to reflect the proportion of pupils on free meals. Not one of the schools in special measures fell in any of the three 'affluent' bands. A small group fell close to the national average, but almost all of them - 96.5% - were in the two upper bands, schools with a proportion of children on free meals which is clearly above the national average.

The evidence goes on and on - from the US, from the OECD, from the EU. There are literally dozens of academic studies which confirm the link between poverty and academic failure. But in the Department of Education, anxious to deliver policies which appear to have a chance of short-term success, the new orthodoxy remains the same. "Poverty is no excuse."

Additional research by Helene Mulholland