Four out of five schools will be worse off next year than they were in 2015, funding campaigners have claimed today.

Despite extra funding being announced by the Department for Education, unions say the vast majority of schools will still be less well funded than they were four years ago.

Geoff Barton, the general secretary of the Association of School and College Leaders, said today’s figures showed that the funding crisis was not over.

The new figures have been released by the School Cuts coalition ahead of education secretary Gavin Williamson’s speech at the Conservative Party conference.

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Earlier this year, ministers announced plans to invest an extra £7.1 billion in schools in England over three years from next year.

The Schools Cuts campaign says that the government has promised to give schools £1.9 billion more next year. However, the unions say this falls short of what is needed.

Mr Barton said: “After years of denying that there is a school funding crisis, the government has finally done the right thing by investing desperately needed extra money into our beleaguered education system.

“But analysis by the School Cuts coalition shows the additional funding is not enough to repair the damage that has been done to our schools and colleges and that further investment is required. We are not being churlish; we are just stating the facts. The funding crisis is not over.”

Kevin Courtney, joint general secretary of the NEU teaching union, said the analysis suggests that Boris Johnson is wrong to claim that government is now “levelling up” school funding across the country.

He said schools would need a 2.9 per cent funding increase just to stand still and meet rising school costs.

And he warned that many schools would lose money in areas where schools forums took the decision to move schools funding into high-needs provision - where there are major funding pressures.

The School Cuts coalition said that about one-third of schools would still experience real-terms cuts to their budgets next year because of rising school costs.

It also warned that sixth-form college students would be the hardest hit.

Luke Sibieta from the Institute for Fiscal Studies said he was not surprised by the coalition’s findings.

“Total school spending per pupil has fallen by 8 per cent after inflation since 2009 and by 5 per cent since 2015,” he said. “The government has committed to extra funding of £4.3bn per year in today’s prices, which will be enough to reverse cuts on average.

“However, that won’t fully come in until 2022. It’s therefore unsurprising to see analysis showing that most schools will have lower budgets in real terms next year as compared with 2015.”

Paul Whiteman, general secretary of the NAHT headteachers’ union, said: “ We won the argument that only new money from the Treasury can solve the school funding crisis. The question now is: how much is enough?

“The additional funding announced by the government is very welcome and will go some way to restoring the real-terms cuts we’ve seen since 2010, but there are gaps.

”Early years, SEND [special educational needs and disability], sixth-form education are all short and schools won’t receive a penny until next year.”

 A Department for Education spokesperson said: “This Government has announced the biggest funding boost for schools in a decade which will give every school more money for every child. We are investing a total of £14bn more in schools over the next three years to 2022-23.

“This means all secondary schools will receive a minimum of at least £5,000 per pupil next year while all primary schools will get a minimum of at least £4,000 from 2021-22 - with the biggest increases going to the schools that need it most. The IFS has said that this investment will restore schools’ funding to previous levels in real terms per pupil by 2022-23.”