Teachers and school leaders have spoken out about the “dire” funding situation in their schools and the “irreparable damage” pupils will suffer because of cuts.

At the ATL teaching union’s annual conference in Liverpool today, delegates revealed how budget pressures had led to redundancies, increasing class sizes and cuts to pastoral provision in their schools.

Josie Whiteley, a governor at a school in Barnsley, said underfunding had left her school with a £500,000 deficit.

“That’s shocking,” she said. “It feels to me as if we’re heading towards bankrupting our education system, and bankrupting the future of all young people in this country.”

“We don’t have any special needs area anymore…we’ve cut to the bone,” she added.

Anne Barker, who proposed a funding motion at the conference, said she had “never known there to be such an acute problem of underfunding with such dire consequences”.

In her area of West Sussex, she said, up to 63 schools have plans for restructuring and redundancies.

Donna Jagger, a deputy head of a primary school in the county, said she had recently written to inform a “standout candidate” for a job that she was unable to employ them because the school could not afford it.

In the same week she also told the parents of a child with severe autism and learning difficulties the school could “no longer afford” to provide him “with the full-time one-to-one support he currently receives”.

“At least we can afford to pay the electricity bill,” she added.

Trevor Cope, a delegate from Devon, said that “redundancy season” had been “extended” because of the cuts.

“To date, I’ve witnessed the removing of almost 150 members of staff from schools in my patch.”

David Healey, the deputy head of a secondary school, said the same pressures were being felt across the border in Wales.

He said cuts had resulted in expanding class sizes, to the point where 70 per cent of the school’s classes now exceed the design specifications of the rooms where they take place.

“It’s desperate… it’s just dire,” he said.

The conference voted for the union to monitor the effects of the national funding formula, to lobby for transitional funding and to challenge the government to increase funding in real terms.

It also voted for the ATL to investigate the levels of SEND support that reaches mainstream schools, and to identify the funding needed to promote mental health in young people.

Maria Viney, a delegate from Somerset, said cuts to mental health support services had compelled her to attend the ATL conference for the first time in her 30-year teaching career.

“I had only been working in this school for a few days when this teenager approached me in a corridor in their break complete with clipboard and a petition that said ‘Stop funding cuts for mental health’.”

The pupil said to her: “Miss will you sign my petition? I’m trying to stop them cutting the money for mental health. You see it’s for people like me and my friends, we need help.”

Ms Viney said: “Why is a child feeling the need and urgency to take this action?

“I was appalled that that’s the state that education is in and that’s why I’ve come to conference for the first time in my teacher career after 30 years.

“We need to ensure that we’re not failing her or future generations.”

The conference also heard from Mike Kane, Labour’s shadow schools minister and a former primary teacher, who said the government should “look objectively at the level of funding required to deliver the best performing schools”, and use this as the basis for a national funding formula.

Mr Kane hit out at the government’s plans for teaching apprenticeships and called for it to put universities back at the heart of initial teacher training.

“If we are to stem the tide [of people leaving teaching] we need to return to being a high status profession,” he said, “not an apprenticeship, which is the direction this government’s wants to go.”

He added: “There are too many routes currently into teaching and I would like to see the return on universities being back at the centre.”