Demands for action on growing violence in schools are becoming as much a fixture of the annual teacher union conferences as those traditional favourites, pay and class sizes.

Leading the field until now has been the National Union of Schoolmasters Union of Women Teachers, which has been monitoring the most serious incidents for almost a decade and claims that its campaign led to the Elton Report into discipline in 1989, the last official look at the problem. The Professional Association of Teachers, meanwhile, has completed a couple of surveys for the Daily Express.

But last week, a third teacher union entered the fray when the Association of Teachers and Lecturers achieved an impressive batch of conference headlines for the second year in a row with its case history of a pupil from hell (later revealed as a Zairean refugee), and a branch survey showing that 90 per cent reported an increase in violence and indiscipline. Only the National Union of Teachers is now remaining aloof from the clamour.

Meanwhile, the Secondary Heads’ Association has just decided to collate figures on the number of attacks reported by members, while the National Association of Head Teachers, although not keeping records, is a vociferous critic of the Government’s latest conclusions on what should be done about disruptive pupils.

The major problem of this debate is the lack of useful statistics. Despite a recommendation in the Elton Report, the Department for Education and Employment does not keep a record of attacks in schools, and has no plans to do so. The Health and Safety Executive is informed of all injury-causing incidents in schools - but until this year no distinction has been made between accidents and attacks.

Local authorities vary in their approach. Some monitor incidents - but will not release figures - while in others the information is buried in individual personal files. And while the NASUWT and the NUT do keep national records, these represent the very tip of the iceberg of incidents in which they have been asked to become involved.

The NUT records 100 incidents in 1992, 115 the following year, and 105 in 1994 - in a union boasting 187,000 active members.

The NASUWT, with 157,146 teaching members, says the number of serious incidents it logged hit a record of 51 last year, one more than in 1987, the year which it says prompted the Elton inquiry. Figures dropped to as low as 10 in 1990.

Given that British schools contain 9,479,000 pupils and 458,000 teachers - more than half of whom are in the NUT and NASUWT - available figures suggest that staff have a considerably higher chance of being hit by a bus than a pupil or parent. Yet anecdotal evidence, such as the ATL and PAT surveys, indicates a higher level of perceived violence which it is difficult to prove or disprove. Figures as high as 11,000 attacks a year have been bandied about, which might well be correct - or entirely wrong.

While professional monitoring of incidents might help to put the issue into perspective - or highlight a genuine national problem - observers point out that even hard figures may not tell the true story.

In East Sussex, for instance, there has been a rise in the number of incidents reported - but officials point out that staff are obliged to fill out forms, and recent raised awareness of such problems has done much to dispel the stigma.

The NAHT complains that police often do not press charges after school assaults, leaving the problems of bringing a private prosecution. And, mindful of public relations, some schools might gloss over incidents, whilst tragedies such as Dunblane might bring on a spate of extra reports. Moreover, there is the difficulty of comparing like with like and the added problem that different teachers may simply perceive behaviour differently. One teacher’s aggressive teenage pupil might be another’s cry for help.

While John Sutton of the Secondary Heads Association is in no doubt that anecdotally, there is a lot more of it about, he suggests that much of the violence directed at headteachers comes from parents rather than pupils - which leads to more questions about school security and society’s views of teachers rather than child discipline.

John Cameron, of the Association of Chief Educational Social Workers, also believes there is a genuine rise in violence in schools, but suggests that increased stresses on teachers have led to changes in the way it is perceived and handled. “I think there is an increase, but I don’t think it is as substantial as some people would make out overall, and it may be more localised.”

One cause may be drugtaking, says Mr Cameron, but changes in schools and society are more to blame. Schools, mindful of their league table positions, are less patient with disruptive pupils who might bring down academic results overall, while teachers have so much extra work that there is less time to help troubled or difficult pupils for whom the recession or family break-up have brought increased problems.

“The changes in job security mean that parents might be told they have to work in Milton Keynes or Edinburgh. It wouldn’t be the first time I’ve come across a 16-year-old looking after a 15-year-old, with both parents holding down jobs to pay the mortgage.

“I think teachers have a lot of pressures of their own and all these extra pressures to deal with. In the past they had more time to do this,” says Mr Cameron. Another problem is that some senior pupils in areas of high unemployment simply see no point in completing their education.

Mr Cameron is concerned that the lack of resources means problem pupils are not given specialist help at an early stage - and also means that pupil referral units, recently cited by education spokesman David Blunkett as part of Labour’s strategy, may also fail to help those in need.

Since the1950s there have been a series of reports into classroom discipline sparked by worries over pupil behaviour. In 1952, the National Foundation for Educational Research concluded that slack management and parental aloofness were to blame.

The 1967 Plowden Report recommended a teacher-child relationship of “mutual respect and affection” and the ending of corporal punishment.

Three years later a report from the teacher unions now known as the ATL and SHA indicated a “slow but certain deterioration in general discipline”.

Next the National Association of Schoolmasters entered the fray, with a 1975 log of disruptive behaviour averaging out at 47 incidents per 100 pupils during a two-month period. Doubt was later cast on this by a Department of Education and Science report which found 7.68 violent incidents per 10,000 secondary pupils.

Three further reports came before Lord Elton was asked to intervene. His inquiry estimated that one in 200 secondary teachers had been subjected to incidents of “a clearly violent nature” during the week under review. Just under 2 per cent complained of physical aggression directed at them during lessons, with just over 1 per cent complaining this had happened during the course of duties around the school. Its 130 recommendations included a strong emphasis on practical training in pupil management.

The final word should perhaps go to Dr Ron Bennett, who was vice-chairman of the Elton inquiry. Unsure whether or not pupil behaviour was worsening, he asked his mother-in-law for advice. She invited him to her old people’s club, where he spoke of rudeness, spitting, vandalism, parents punching teachers and one boy hitting another with a spade.

His audience was horrified. “Our teachers would not have allowed that to happen,” they claimed. Dr Bennett then revealed the incidents came from the village school log book of 1910-1920. The audience’s attitudes changed entirely, and finally one man confessed: “I did it. I was the one who hit the boy with the spade - and I’d do it again. The bugger deserved it.”