The footage from Whitefield School in north-east London resembles “torture”, one safeguarding expert told us. It shows for the first time the reality of what pupils faced.

A police investigation into the abuse footage, taken inside the special school’s “calming rooms” between 2014 and 2017, ended earlier this year without any charges. However, parents say they have been left to deal with the trauma.

The school says new leadership found the footage after the rooms had been shut and shared it with the police.

About 40 children with learning disabilities and severe mental disorders were confined for hours in the rooms – typically without food or drink.

Six of the families have agreed to have footage to be broadcast. They wanted us to reveal the scale and severity of the trauma their children had experienced – which they feel they have been misled about.

The videos show pupils, many of whom were non-verbal, clearly in acute distress, and many are seen to injure themselves for prolonged periods.

In the footage, the only time staff at the school in Walthamstow intervene once children are inside the rooms is when a boy repeatedly throws his shoes at the CCTV cameras. They race in to stop him, with one teaching assistant apparently striking him.

“It broke my heart,” said the mother of one of the abused children after viewing the CCTV for the first time. “You wouldn’t even do that to a dog.”

Even now government guidance says only that removing disruptive pupils from classrooms in England must be for a “limited” duration and facilities must be “suitable”.

There is evidence of mistreatment in seclusion rooms at other schools across the UK. One autistic child was kept inside a cage.

Meanwhile, local MP Sir Iain Duncan Smith said the Whitefield School footage “must lead to profound change” and described it as “jaw-dropping”.

Safeguarding expert Elizabeth Swan said it was “easily the worst footage” she had seen.

“You look at the children and they’re being defeated and responding to that treatment with self-injurious behaviour, it’s torture,” she said.

Whitefield School was rated as outstanding until, in 2017, Ofsted discovered the use of bare, padded rooms without windows to seclude children.