A union leader has said a headteachers’ march on Westminster will be the best day’s work they have ever done if they can persuade ministers to put more funding into education.

A thousand heads are set to descend on Downing Street today to protest against the real term funding cuts their schools have faced over the last eight years.

The campaign group Worth Less? will deliver a letter to chancellor Philip Hammond urging him to reverse real-terms cuts and put an extra £400m to support SEND and high-needs pupils.

The general secretary of the NAHT heads’ union, Paul Whiteman, has issued a rallying call ahead of today’s event.

He said: “School funding is the public service cash crisis that the government refuses to deal with. It’s still a doorstep issue for voters, and until the Treasury announces more money for education, school leaders, governors, parents and others will continue to make their voices heard.

 “Headteachers are not normally the marching kind. So, when they do, it must be serious.

“They’re sick of being told that there’s more money in education than ever before, when what they see with their own eyes every day proves that it’s just not enough.

“More and more now, children succeed despite the system, not because of it. And that can’t be right.”

High profile head Vic Goddard is among the school leaders taking part today.

Writing for Tes he says he hopes the march will change the Government’s approach to the issue.

“I think we all crave is honesty from the government. The oft-trotted-out line of ‘more funding going into schools than ever before’ is the educational equivalent of ‘strong and stable’ from the last election. It has been proven time and again to be disingenuous at best.

“Honesty alone will get us more on board than we are right now.”

Mr Goddard, who rose to prominence in the Educating Essex TV series and is a founding member of the Heads Roundtable group, added: ” I have been lucky to be given access, since being on the telly, to people in government that others don’t and feel this comes with some responsibility.

“So when I see the figures that 86 per cent of schools have reduced teaching assistant hours to balance the budget this year it rings huge alarm bells - I feel obliged to speak up. 

“As money gets tighter it is our most vulnerable young people that are likely to suffer most and that is unacceptable.”

The NAHT says their research shows that almost three-quarters of school leaders expect they will be unable to balance their budgets in the next financial year. 

Earlier this year, figures showed the number of secondary schools in England running at a loss had nearly trebled in four years.

The study, by the Education Policy Institute (EPI) in March, said the number of local council-run secondary schools in deficit dropped from 14.3 per cent in 2010/11 to 8.8 per cent in 2013/14, but between 2013/14 and 2016/17, the numbers in deficit nearly trebled to 26.1 per cent.

In July, the Institute for Fiscal Studies said total school spending per pupil has fallen by around eight per cent in real terms in England between 2009/10 and 2017/18.

And heads concerns about rising costs not being matched by funding have been added to after being told this week that they must increase contributions to the Teachers’ Pension Scheme by 43 per cent from next year.

Mr Whiteman said: “It’s a cliché to say that children are our future. But it is true. Failing to invest in them is a failure to invest in the future of the nation. Saving money on education is a reckless false economy.

“What we need is for the government to show some leadership and properly fund the essential work all schools do.

“One teacher said to me recently that if we go to London today and get the Treasury to change its funding policy, he reckons that will be the best day’s work he’s ever done. That’s the stage we’re at.”

The letter to be presented to Mr Hammond, seen by Tes, will call for the government to: 

• Fund all schools adequately and reverse the real terms cuts that have happened over the last eight years.

• Make an immediate £400 million cash injection to support SEND and high needs.

• Meaningfully improve real terms per pupil funding for the post-16 education sector.