ALL the headteachers in Darlington will today issue a cash crisis alert as a teaching union warned chronic underfunding at North-East and North Yorkshire schools would lead to unprecedented cutbacks.

Heads of 31 primary and eight secondary schools in the town have united to send a letter to parents, urging them to lobby the government before a £7m black hole develops in their budgets by 2020.

Education experts said unless action is taken the lack of funds would lead to swelling class sizes, fewer teachers and a skeletal curriculum being imposed.

The letter from primary heads states: “We don’t want to cause panic and we will do our very best to continue to provide the best possible care and education for your child, but you will agree that it isn’t possible to do more with less.”

Across the region, the NUT said schools in North Yorkshire would be £21.5m worse off in 2020 than 2016, in County Durham £20m down, and in Middlesbrough £11m poorer. Hartlepool, Redcar & Cleveland, and Stockton's schools would be £5m, £7.7m and £8m down respectively.

Among the hardest-hit schools in Darlington is Skerne Park Primary, which by 2020 will have seen its budget slashed by 24 per cent, followed by Gurney Pease Primary at 21 per cent, according to figures from the NUT. Carmel College is the worst-hit secondary school, with a decrease in funding of over a fifth, 21 per cent, in the years from 2013/4 to 2019/20.

Funding for pupils has been likened to the 1950s, with some schools in the town losing almost a quarter of their budgets in just six years.

The National Union of Teachers said the North-East's small rural schools would be among the hardest hit under the Government's planned revised funding formula for schools.

Nationally, schools will be £3bn worse off, due to rising costs and increased pupil numbers, combined with a budget freeze, according to the website, which is based on official data.

Parents in Darlington are being asked to write to Education Secretary Justine Greening and Schools Minister Nick Gibb.

Hurworth School head Dean Judson coordinated the letter after heads expressed dismay after Chancellor Philip Hammond stated in the Budget there was more money in education than ever before.

The secondary schools' letter warned: "Rising costs and a frozen budget mean tough decisions may have to be taken. We cannot guarantee that such cuts will not impact on teaching, despite us doing our utmost to prevent this."

The town's primary schools heads added: "This lack of regard for the next generation really worries us. We are not a political or militant body. We are a like-minded collection of head teachers who want the very best for the children."

School costs are set to rise by eight per cent year-on-year, while funding has been frozen from 2010 to 2020. This is combined with rising national insurance, pension, utilities and service costs.

NUT regional organiser Mike McDonald said: "The government has plenty of money for its vanity projects such as setting up academies, free schools and grammar schools, but not enough for state education."

A Department for Education (DfE) spokesman said the core schools budget had been protected since 2010, with school funding due to reach £42bn, its highest level, in 2020, and pledged to "end the postcode lottery" with the new national schools funding formula. He claimed in Darlington school funding would increase by one per cent under the formula.

He said the DfE would support schools in cutting costs, such as the way services and goods are bought.

A consultation on the funding formula runs until Wednesday.