The letter stated that the current level of funding was “inadequate” and the new funding formula would not improve matters because there is not enough money in the overall pot.
As previously reported by Public Finance teaching unions have warned that the new funding formula did not go far enough.
Jules White, head teacher at Tanbridge House school in West Sussex, said a lack of resources had led his school to lose five full-time members of staff and restricted its ability to purchase new books and equipment.
“We are even down to the fact that we don’t even get to clean our school properly [due to lack of resources], these are fundamental issues that need to be put right,” he added.
These concerns were expressed in the letter to Philip Hammond, which warned that because of forecast real-terms cut of £1.7bn between 2015 and 2020 schools face recruitment and retention problems, growing class sizes, withdrawing certain subjects and closure of sixth forms.
Angela Rayner, Labour’s shadow education secretary, said the government had to “start listening”.
She added: “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.”
Nick Gibb, the minister for school standards, said the introduction of the national funding formula from 2018-19, is backed by £1.3bn of additional investment, which will “put an end to historic disparities” in the system.
Gibb continued: “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.”
The protest, ahead of next week's Budget, was organised by regional groups of head teachers representing schools with more than 3.5 million pupils across 25 local authorities from Cornwall to Cumbria amid claims their regions will receive much less funding than others.
