Nearly 2,000 school leaders have voiced their grave concerns over Ofsted’s plans for a controversial new inspection framework – with an overwhelming number agreeing the union should consider options for industrial action should the proposals go ahead.

A snap poll carried out during an online meeting specially convened by school leaders’ union NAHT found that almost nine in 10 union members – 89% - supported the union exploring industrial action options.

The leaders, whose schools are between them responsible for the education of nearly 900,000 pupils, aired serious worries about the planned new system, which is due to come into effect in November.

They included concerns that the continued use of crude grading would perpetuate a high-stakes inspection regime. They said this would harm the well-being and mental health of themselves and their staff, while failing to offer parents a reliable gauge of schools’ effectiveness.

Members expressed concerns that Ofsted and the government appeared to have lost sight of the original rationale for the reforms – the tragic death of Berkshire head teacher Ruth Perry following an inspection more than two and a half years ago.

Paul Whiteman, NAHT’s general secretary, said: “This was the biggest turnout we have had at a meeting of our members since the pandemic, and the strength of feeling was palpable.

“We heard loud and clear that these plans simply do not have the support of the profession and should not go ahead in their current state.

“Rolling them out would pose clear risks to the health and wellbeing of school leaders and teachers

“The worrying findings of Ofsted’s own independent wellbeing assessment should have been a red flag, but instead it has rushed ahead regardless, tinkering around the edges while failing to properly work through the recommendations of this assessment.

“We will now liaise with our national executive committee to consider next steps - but we are appealing once again to Ofsted and government to put the brakes on these hugely flawed plans.”

Angi Gibson, NAHT’s president, added: “Ofsted claims to have the support of parents - but as a serving primary school head teacher it is clear to me that while Ofsted’s proposed report cards may appear to offer clear information, it will be far from accurate or reliable.

“This framework not only continues with grading but extends it. It will be impossible for inspectors to judge schools definitively across so many areas during what is simply a two-day snapshot.

“It risks unfair judgements, which mislead parents, while also piling workload onto schools.

“Parents were not asked if they would support a system which serves them with unreliable information while damaging the wellbeing of school leaders and teachers, and in doing so potentially impacting their children’s education.

“We very much doubt parents would want this outcome and urge the government and Ofsted to think again.”