Overwhelmingly, teachers are “can do” people. Usually optimistic, even against apparently overwhelming odds, teachers make do, cut their cloth to suit their (curriculum) coat, keep calm and carry on.

But teachers tell me that they can no longer cope with the budget cuts being imposed on their schools. Many felt the pain of the deputy headteacher of Marlwood School, featured in last week’s BBC2 episode of School, who, barely able to keep her emotions in control and with tears in her eyes, declared: “We love our school. It’s just the unfairness. Cut after cut after cut.”

Viewers subsequently learned that this dedicated teacher had, after 22 years, left the profession. What a waste.

In a survey conducted earlier this year by the National Education Union, teachers told us a sad and similar tale. Almost all said that they were pessimistic about their school’s budget prospects. More than half said that class sizes had risen and teaching-assistant posts had been cut. This double whammy has meant a massive increase in workload for teachers. One of whom, who works in a primary school, said to me recently: “I have a teaching assistant in the mornings, but am left on my own with 32 children - four [of whom are] on the autistic spectrum and one with mobility issues - every afternoon. I am simply unable to cope.

“I can’t give the SEND [special educational needs and disabilities] children the support they need to access learning and I let down the others because I simply don’t have the time to give them the attention they deserve.”

This teacher is leaving the profession at Christmas.

Average working weeks of 55 hours are increasing because of school funding cuts. Teachers have reported that resources are being cut. Many are buying books and equipment out of their own money. One teacher wrote: ”It is hard to encourage children to love reading when all our books are falling apart!”

In another survey, teachers reported that schools were not supporting the development of their students’ IT skills because of a lack of funding. Nearly 18 per cent of teachers felt that digital skills were not being developed in school because of a lack of funding. One wrote: “We have just got rid of our virtual learning environment (couldn’t afford it) and have very limited access to computers/technology in school (again, not a funding priority).”

‘Something has to give’

School budget cuts affect teachers and pupils in another, important, way: they have to work in buildings that become increasingly dilapidated and dirty. One wrote: “Cleaning has been cut so the school is filthy. Basic health and safety issues are not being addressed, such as inadequate lighting in workshops.”

Last year, the House of Commons Public Accounts Committee revealed that it would cost £6.7 billion to return all school buildings to satisfactory or better condition, and that the cost of dealing with major deficits in school buildings would double within the next five years, as many buildings were near the end of their useful life.

And, as they struggle on in deteriorating conditions, with workloads rising directly because there are more pupils and fewer teachers and support staff, teachers also find that their wages are being suppressed. More than a quarter of the secondary school teachers who responded to the NEU survey said that there had been issues in their school about annual pay rises not being implemented, or pay progression being withheld.

In the end, something has to give, and the biggest casualty of the school-funding crisis is teachers, who are walking away from the profession.  One-third of newly qualified teachers now leave within the first five years of their career - a brain and talent drain that, more than anything else, is threatening standards of education in our schools.

And that is why the NEU, along with the Association of School and College Leaders (ASCL) and the NAHT headteachers’ union, is saying enough is enough. We cannot stand by and do nothing. Our children and young people only get one chance at school. They need, and deserve, to be educated in clean, safe school buildings. They have a right to be taught by well-trained, well-qualified teachers who are paid appropriately for the essential work that they do. They need adequate resources to support their learning. And none of these essentials should be paid for by parents, too many of whom are struggling to feed and clothe their children.

And so the NEU, along with ASCL and the NAHT, is surveying all their teacher and school-leader members, asking them whether they believe that funding cuts are having a negative effect in their school. We are asking teachers and school leaders whether they believe the government should fully fund and implement the recommendations of its own teachers’ pay review body. And we are asking members whether they think their unions should continue to campaign on school funding.

NEU members are being asked whether they would be prepared to take strike action to secure better funding for schools and the full implementation of the teachers’ pay award - which should have been 3.5 per cent for all teachers and school leaders.

This Friday is #FundingFriday - a day when we are asking all NEU members to hold meetings in their school to discuss the effects of funding cuts on their schools and to vote in the ballot. Because if not now, when?

How bad does it have to get before even more teachers decide that enough is enough and leave the profession? If you judge that we cannot simply keep carrying on, the time is now to make a stand.

Mary Bousted is joint general secretary of the NEU teaching union. She tweets @MaryBoustedNEU