Researcher Carol Hayden found all the excluded pupils she investigated had experienced a variety of stress factors - including family breakdown, serious accident, unwaged parents. The average number of such stresses for the children in her study was 6.7, but one boy had 11. “The only thing he hadn’t suffered was a major accident. It’s quite an achievement that he was in school at all with that degree of turmoil in his life. Everything was happening to that kid,” said Dr Hayden.

Excluded children were also likelier to be male, with special educational needs (usually emotionally and behaviourally disturbed), underachieving, large for age, new to the school with few or no friends, low self-esteem, black or mixed race and with high levels of hyperactivity or similar problems.

Tipping the balance for such children was the school itself. If it was suffering financial cuts, staffing problems, or was overcrowded, the problem child was likelier to be excluded. This risk was also exacerbated if the school had been forced to take the child or misinformed about his needs or personal circumstances.

Dr Hayden, who works at the University of Portsmouth, investigated 265 children excluded in three local authorities for the Economic and Social Research Council-funded project, taking detailed case studies from 38. Exclusion rates varied enormously among the one shire and two London authorities and also between individual schools.

She said she had embarked on the project in the knowledge that exclusions from primary schools had risen from 378 in 199192 to 1,215 the following year. Dr Hayden had originally assumed that this was because schools were getting rid of troublesome pupils more readily because of increasing pressure of market forces, but her research had led her to the conclusion that many troubled children were only still in education because of the dedication of school staff. “It really depends on the luck of the draw,” she said.

It is this lack of planning and support for troubled children which she would like to see tackled, perhaps with school-home support workers who can monitor all the problems in a pupil’s life or on-site counselling for children and parents.

A child’s social worker might not be the obvious choice for such a task because keeping the pupil in school might not be the top priority, said Dr Hayden.

The exclusion of primary children was still a rare event, and the children involved often exhibited extremely disturbed behaviour rarely seen by teachers, such as hiding under desks and making animal sounds or being extremely aggressive.

Dr Hayden found high levels of informal exclusion - such as sending difficult pupils home at lunchtimes or for other parts of the day - in the study. The informal exclusion rate was running some eight times higher than the official figures, but in some cases, it is only this which enables the school to retain the child at all.

Dr Hayden concludes that market forces and the national curriculum may have made it less attractive to take children with emotional and behavioural problems. Other factors include the move away from residential care and the rapid movement in and out of placements for children who are unsuccessfully returned to their natural parents or go in and out of foster care and children’s homes.

THE STRESS FACTORS WHICH MAKE EXCLUSION MORE LIKELY

* family breakdown

* time in caresocial work involvement

* multiple movesdisruption

* disabilitybereavement

* violenceabuse

* major accidentincident

* policecourts involvement

* substance misuse

* special education needs statementformal assessment in class

* previous serious exclusion

* no member of household in paid work