Headteachers will march on Westminster next term because they are now "desperate" for the government to act on school funding, a union leader has warned.
The NAHT headteachers' union general secretary, Paul Whiteman, told Tes that the frustration felt by school leaders over the funding shortfall was now as strong as he has ever felt it.
A grassroots school funding campaign will hold a second march on Westminster on 27 September, with as many as 5,000 school leaders expected to take part.
It is being organised by the Worth Less? campaign and is backed by the NAHT.
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One leader planning to take part said headteachers were marching again because "it's the only thing left we can do".
Action on school funding 'has to be taken now'
Mr Whiteman said: "Our members are increasingly asking us how they can vent their frustration at the government over school funding and, from the calls we are getting, I would expect that to be reflected in the numbers on this march.
"They are increasingly desperate. The sense of frustration among the profession is as strong as I have ever known it.
"Schools can’t wait until 2022 or until Brexit is sorted for this money – action has to be taken now. Schools are having to make cuts from this September, so they need urgent relief."
Mr Whiteman said the Department for Education needed to provide immediate short-term financial relief to schools and then produce a budget or spending review setting out plans for education funding. He also said the NAHT backed the Commons Education Select Committee's calls for a 10-year funding plan for education.
In September 2018, a march organised by Worth Less? involved 2,000 heads taking to the streets of the capital to call for more money for schools.
The head of Worth Less?, Jules White, said he expected this year's march to be even bigger amid uncertainty over the future of school funding.
He said: "Heads are absolutely supportive and the fact that Worth Less? has grown to cover 75 local authorities underlines the strength of feeling among heads across the country.
"Recently heads from areas like Shropshire and the Isle of Wight have expressed a desire to be involved. We are adamant that we will not see pupils, families and schools fobbed off with a short-term funding gesture."
Mr White added: “Cost pressures and pupil numbers continue to rise while schools feel completely and unfairly overstretched by a growing need to cover off social care and even some police duties.
“We know that the new government has pledged an increase in funding but we are very concerned that when the detail is understood an improvement that looks good on paper will take too long to come through and provide little by way of certainly for a long-range and real-terms increase."
Sabrina Hobbs, the head of Severndale Specialist Academy in Shrewsbury, one of the largest special schools in the country is among the school leaders planning to march.
School funding system 'is broken'
She said: "Like most schools, Severndale Academy has changed and adapted our structures year on year to accommodate and meet these financial demands. The system is broken and needs a new approach.
"There is no sustainability to the current funding structures which will affect our future generations. We are now at the tipping point and that is why more leaders are prepared to march for change because its the only thing left that we can do."
Last week the new prime minister, Boris Johnson, repeated his plans to increase school funding. During his campaign for the Conservative Party leadership, he pledged an extra £4.6 billion for schools by 2022-23.
However, he failed to answer a call to say when schools will be given details of their funding settlement to enable them to start planning, when he appeared before MPs as prime minister for the first time.
A DfE spokesperson said: "The prime minister has made clear that we will increase minimum levels of per-pupil funding in primary and secondary schools and return education funding to previous levels. We will make further announcements in due course.”
Unions and headteachers' leaders have also reacted angrily to the DfE's announcement that this year’s 2.75 per cent pay award for teachers will not be fully funded by the government.