The woman, from the West Midlands, suffered a neck injury and still has to wear a surgical collar, six years later. The case, taken up by the National Association of Schoolmasters Union of Women Teachers, was settled by the local authority just before it was due to go to court.

Larger sums have been awarded to teachers in special schools and young offender centres, but the union believes this is the most compensation for a teacher assaulted by a pupil in a mainstream school.

The union receives about 20 calls a week from members who have been attacked by pupils, parents or intruders. However, teachers who are assaulted at work are being discouraged from contacting the police by some governing bodies who are concerned about the reputation of the school.

According to Jerry Bartlett, the NASUWT’s legal aid and benevolence officer, writing in the union’s magazine Teaching Today, heads and governors are often extremely critical of teachers who attempt to take action. They say it could damage a school’s reputation and lead to redundancies in the event of falling rolls.

The union claims a significant breakthrough with the Pounds 82,500 case. The pupil involved had a history of behaviour problems since his admission to nursery school. His teacher was attempting to persuade him to return to class after he refused to take part in a lesson. First he shouted abuse at her, and then hit her under the chin. The woman still has difficulty in moving her neck.

The union says the case should focus the attention of school management on the need to protect staff from children known to be violent, and on providing a safe working environment.

Mr Bartlett said his union will be encouraging and supporting teachers who have been attacked to bring legal action against their assailants. But there are legal constraints: a child under 10 cannot be held capable of criminal responsibility.

“A pupil over the age of 10 but under 14 can be prosecuted if, with reference to the child’s particular background and the surrounding circumstances of the offence itself, it can be proved that the attacker knew that what he did is seriously wrong.

“Paradoxically it is difficult to succeed with an offender of that age group from a home where a criminal lifestyle is the norm,” he said.

The union is also concerned that governing bodies are being too lenient to pupils who act violently in schools. The NASUWT has supported members in a number of schools who have refused to teach violent pupils they believe should be excluded.

In a recent case, an NASUWT member was assaulted by two pupils from a neighbouring school. His neck was injured after he approached the boys after finding them acting suspiciously. A letter was sent to their home and the boys were suspended for two days.