Media playback is unsupported on your device Media caption The Panorama programme uses never before broadcast footage of the Hillsborough disaster

Crucial evidence from the 1989 Hillsborough football disaster, which was undermined at the original inquest, was true, BBC Panorama has found.

An off-duty police officer has always maintained he tried to treat a dying boy after the time at which the coroner said no-one could have survived.

His account cast doubt on medical evidence that supporters could not have survived beyond 15:15 on that day.

Panorama's analysis of unbroadcast TV footage shows his account was true.

Ninety-six football fans died after they were crushed to death on 15 April 1989 during an FA Cup semi-final between Liverpool and Nottingham Forest at Sheffield Wednesday's Hillsborough stadium.

The inquest at the time resulted in verdicts of accidental death but, in December last year, the High Court quashed those verdicts and ordered fresh inquests to take place early next year.

The TV footage seen by Panorama calls into question the response of the emergency services on the day.

The Hillsborough Independent Panel's report into the disaster - published last year - analysed the medical evidence.

It found that given proper treatment, more than half of the 96 fans who died, including the 15-year-old boy, Kevin Williams, might have had a chance of survival.

Overcrowded terraces

Off-duty Merseyside police constable Derek Bruder, who tried to resuscitate Kevin, was one of those whose evidence was undermined at the inquest.

The Hillsborough disaster was recorded by seven BBC Sport cameras, and a BBC news team, while the police had CCTV and a mobile camera unit.

As a life-long Liverpool fan, I was there that day and reported on it for the BBC News that night.

Image copyright Hillsborough Justice Campaign Image caption Kevin Williams was 15 when he died

The BBC footage was later released to the police and the families' lawyers but it was then locked away as it was considered too distressing for broadcast.

Some 24 years on, Panorama has been able to analyse it.

It shows how things went wrong from the start at Hillsborough and continued going wrong for longer than has ever been admitted.

At 15:06, the football match was stopped as Liverpool fans escaping the overcrowded terraces ran onto the pitch.

At 15:28, Kevin Williams was pulled out of gate three and laid on the pitch. Soon after, he was carried across it. A fan who tried to help him believes he was still alive.

Kiss of life

Steve Hart said: "I remember shouting to everyone to pick him up and get down there with him, you know, you're looking at people everywhere and you're thinking, obviously my instinct was this lad needs help."

PC Bruder was photographed kneeling on the ground giving Kevin the kiss of life, but he was not sure at what time the photograph was taken. PC Bruder told Kevin's mother, Anne, how he had tried to help her son.

"He told me then what he'd done for Kevin and I said 'Was my son alive?' and he said 'Well, if you say finding a pulse with the first two fingers... if that means he was alive, then he was alive'," she said in one of her last interviews before she died last month.

But the coroner at the original inquest ruled that all those who died that day had been beyond help by 15:15.

Media playback is unsupported on your device Media caption Doreen Jones: "I wanted to touch my son, I wanted to hold him"

This decision meant the response of the emergency services was never properly investigated.

A fleet of ambulances was parked outside the football ground, but crews and emergency equipment were not sent inside.

Tony Edwards, who was on board one of the few ambulances that entered the ground, said: "I always think in terms of a rail accident. Could you imagine the public outcry if all ambulance crews remained on an embankment simply because they couldn't get the ambulance down to the scene of the accident?

"That doesn't happen. They get out of their vehicles and if that's the length of a football pitch, they have to go, they make their way there."

Ambulances on pitch

PC Bruder said an ambulance was arriving and driving past as he treated Kevin, but he was not called to give evidence at the inquest.

Instead his evidence was outlined to the coroner by a West Midlands police officer. He mentioned only two ambulances going onto the pitch, both before Kevin was carried to the end where PC Bruder tried to save him. As a result, PC Bruder's evidence was considered unreliable.

But the footage analysed by Panorama shows that a third ambulance turned up after 15:30.

Mr Edwards was the ambulance man in the third vehicle and said the West Midlands Police officers investigating the disaster knew this before PC Bruder's evidence was undermined at the inquest.

"They had a video set up, they had photographs and they had laid out photographs as well and it was them who said to me, 'I want to show you your vehicle coming on the pitch at 3:35'," he said.

The footage also shows the moment PC Bruder goes to help Kevin. It is after 15:30 and proves he had been right all along.

PC Bruder has told Panorama he has now made a complaint to the Independent Police Complaints Commission about how his evidence was handled.

West Midlands Police said it would co-operate with the IPCC and could not comment while inquiries continued.

Yorkshire Ambulance Service NHS Trust said it would co-operate with any new legal inquiries.

Watch the Panorama Special - Hillsborough: How They Buried The Truth on BBC One at 21:00 BST on Monday, 20 May.