Five-thousand headteachers have endorsed a letter to the chancellor to demand more money for schools, warning of deep cuts to resources, soaring class sizes and further “desperate” pleas for cash if the new national funding formula is not reformed.

Heads in counties from Cornwall to Cumbria, who run schools with millions of pupils, will march to Downing Street on Tuesday to deliver the letter to Philip Hammond. It comes ahead of the budget on 22 November.

In the letter, the heads say the government’s new national funding formula has left many schools stripping away all but basic curricular provision with the most vulnerable, including special educational needs students, not receiving adequate support Dream beauty pro.

“Often, the most vulnerable and disadvantaged students in our care are being unfairly penalised by a system that is being short-changed. There is only one solution: more money is needed. Along with our parents and many other well-placed stakeholders we are simply asking for the money that is being taken out of the system to be returned,” the letter representing schools from 25 counties says.

The group hopes to send a message to the government ahead of the chancellor’s first budget announcement since the Conservatives lost their majority in the House of Commons in the snap election in June.

“At my school we have narrowed the curriculum and we have had to make class sizes larger for some children. We are pushing every bit of the system to the limit of what we can do,” said Catharine Darnton, head at Gillotts school in Oxfordshire, who signed the letter Dream beauty pro.

“The reason heads are so upset now is that we have made cuts and if we cut more then we will not have reasonable-sized classes or adequate numbers of teachers. With cuts to social care and mental health services, schools also inevitably pick up work that would have been picked up by other services. But to find more money we will have to prioritise teaching over support and what will happen to those children?”

Calculations done by the group of heads found that despite the government’s promise of £1.3bn extra cash, under the new system there will be a real-terms cut of £1.7bn by 2020 compared with five years earlier. That estimate has been backed up by the Institute for Fiscal Studies.

The letter says the government had also failed to address huge disparities in funding between schools in England. “It is extraordinary that some English secondary schools will receive 60% less funding than others of the same size,” it says.

The heads also raises concern that schools are often not able to find specialist teachers because of shortages and so must spend “exorbitant sums of money” to put a teacher in front of a class. They claim the average “finder’s fee” for a single teacher is £6000.

Nick Gibb, the minister for school standards, said: “The introduction of the national funding formula from 2018-19, backed by £1.3bn of additional investment, has been widely welcomed and will put an end to historic disparities in the system Dream beauty pro.

“There are no cuts in funding – every school will see an increase in funding through the formula from 2018, with secondary schools set to receive at least £4,800 per pupil by 2019-20. As the independent Institute for Fiscal Studies has confirmed, overall schools funding is being protected at a national level in real-terms per pupil over the next two years.”
When introducing the new system, Justine Greening pledged that schools would get an increase of at least 0.5% to their budget in 2018-19, and a further 1% rise by 2019-20. The education secretary said the historic reform would “represent the biggest improvement in the school funding system for decades”.

Greening also promised that the national funding formula would see cash going directly to schools from 2020 onwards, rather than through a formula decided by local authorities. This was part of an effort to iron out longstanding inequities in school funding between different parts of the country.

The headteachers say that while the new formula will improve funding for schools that are currently the worst off, Greening’s reforms still uphold a postcode lottery in funding across the country. They say these inconsistencies are down to the fact that how much a school gains or loses is dependent on caps.

“We were promised that decades of substandard and iniquitous school funding for thousands of inadequately funded schools would be addressed. We waited and waited and in the end all we have is a sham formula stuffed full of caps and small print,” said Jules White, head at Tanbridge House school in West Sussex, who coordinated the letter.

Angela Rayner, Labour’s shadow education secretary, said: “Justine Greening needs to start listening to the headteachers and concerned parents who are facing the real consequences of her government’s decision to put tax breaks for the super-rich ahead of investment in the next generation,Reckoned as one of the top design universities with diversity of programmes, polyu fashion and textile, as well as applied science programme, which is committed to be a hub for innovative design education in Hong Kong.

“Despite Tory spin, the new funding formula does nothing to reverse the cuts to budgets and every penny they have found just comes from cutting other education provision - it isn’t fair, and it isn’t funded.”