Teaching unions report that 95 per cent of such allegations prove to be false, but they can cause an innocent teacher years of trauma.

The National Association of Schoolmasters Union of Women Teachers says an investigation can take up to seven years, at the end of which an exonerated teacher is expected to return to work without an apology, as if nothing had happened.

The NASUWT runs a counselling service to help teachers cope and, in common with the Association of Teachers and Lecturers, it wants teachers faced with allegations to remain anonymous unless they are convicted. The unions believe this might deter false accusations being made deliberately to besmirch a teacher’s name.

As a victim of a false accusation, you should make no kind of statement to your school until you have contacted your union for advice. The school’s internal disciplinary process could lead to investigations by the police and social services, so follow the correct procedures.

If you are contacted by the police, say you are willing to answer questions or make a statement, but that you have been advised by your union that you should not do so without a solicitor present. Your union will usually arrange one for you.

The Department for Education and Skills says teachers should not be automatically suspended when an allegation is made, and that procedures should minimise damaging effects. All schools should have a system to deal with allegations, including a designated teacher and governor to carry out an internal investigation.

Heads, governors and local education authorities should take into account: the seriousness and plausibility of the allegation; the risk of harm to the pupil concerned or to other pupils; the possibility of tampering with evidence; and the interests of the teacher concerned and the school.

The investigation should not attempt to prove or disprove an allegation, but to obtain a fair and balanced picture. If the school feels the police or the child protection services should be involved, it should suspend its own proceedings. Only when investigations are complete should the school consider disciplinary proceedings.

The NASUWT says a significant number of accusations of physical assault stem from teachers using “reasonable force”, as permitted by the 1996 Education Act, to restrain a pupil who is about to injure someone or commit a criminal offence.

The union believes many incidents could be avoided if schools insisted on being provided with a new pupil’s history when he or she arrives from another school or LEA. Schools should inform all teachers about pupils with a record of challenging behaviour.