Jay Burkinshaw, from Stoke on Trent, said colleges were becoming the new pupil referral units (PRUs) as problems were pushed further and further up the education system.

She told the National Association of Schoolmasters Union of Women Teachers’ conference in Bournemouth that disruptive pupils were often shoved into practical classes in colleges. “To my mind risk assessment is even more important then, because you have someone who could hit you over the head with a spade,” she said.

Delegates said they could not accept the principle of unqualified inclusivity, and said that if severe disruption in schools was to be managed, properly-resourced PRUs needed to be established.

Employers had a duty to identify hazards posing a risk to health and safety in the workplace and to ensure the welfare of their employees. But, said the NASUWT, many parents wanted their children to be disciplined at school in an attempt to avoid confrontations at home.

And it warned that unless the serious symptoms of indiscipline were tackled firmly and at an early stage, the initial problem would become endemic.