A schoolboy miraculously pulled alive from the rubble of the Aberfan disaster has met two of his rescuers for the first time - five decades on.
In October 1966, the mining village of Aberfan in south Wales was hit by an avalanche of coal waste which claimed the lives of 114 children and 28 adults.
Youngsters in Pantglas junior school were just getting ready for lessons when without warning, 1.5 million cubic feet of liquefied slurry plummeted down a hillside and almost wiped out an entire generation.
Now almost 50 years to the day, survivors of the tragedy have shared their stories in a new BBC documentary revealing how the events of that fateful day left not only physical but also emotional scars.
Phil Thomas was 10 when the 150,000 tonnes of waste smashed into his school and a number of neighbouring houses with a tsunami-like force.
En-route its final resting place, the avalanche had fractured two pipelines and sent hundreds of gallons of water rushing into already saturated sludge.
The youngster lay trapped under a collapsed wall in the dark of the brown-black debris while a group of rescuers faced a battle against the clock.
He was pulled from the rubble by a group of six men - who included Len Haggett and Dave Thomas.
Former firefighter Mr Haggett has publicly retold of the dramatic rescue for the first time in in the BBC documentary Surviving Aberfan - which saw an emotional reunion between the pair.
He said: "The in-rush of water started and you could hear people calling 'the water was coming' ... and we had to hold his head up out the water.
"How we lifted that wall that day I don't know, but raise it we did and long enough to get our arms around his shoulders.
"If he hadn't have come out he would have drowned ... the fact that a young boy had been saved ... there was elation."
Mr Thomas, 60, who also lost three fingers that day, was brimming with emotion after finally meeting the duo who plucked him from certain death.
Fighting back the tears, he said: "Until this day, I never knew who dug me out. I would like to thank both of you."
His amazing reunion is one of several and moving accounts featuring in the BBC programme.
School dinner lady Nansi Williams grabbed a group of children and flung herself on top of them to take the brunt of the impact when she realised something terrible was happening.
Karen Thomas, one of the pupils saved by the heroic act, has made regular visits to Mrs Williams' grave ever since.
"It's only down to Nansi that I am here today," she added.
And despite losing a kidney from the harrowing ordeal, she added: "I was one of the lucky ones to come out."
The disaster unfolded after millions of cubic metres of excavated mining debris from the Merthyr Vale Colliery came thundering down the hillside.
The waste material had been piled high on the side of Mynydd Merthyr - above the village of Aberfan - for years even though there were numerous underground springs below.
And at 9.15am on a foggy October 21, 20ft of material from Tip Number Seven became dislodged with devastating consequences.
Like many of the survivors, Friday's 50th anniversary will bring back painful memories of the disaster.
Jeff Edwards, who was the last child to be brought out of Pantglas Primary School alive, said he has been plagued by nightmares over the years.
Future Merthyr mayor Mr Edwards had just picked a new library book and walked back to his desk when he heard a gigantic rumbling sound.
He added: "The teacher said. 'It's only thunder, it will go soon', then the next thing I remember was waking up and hearing shouts and screams."
For two hours the eight-year-old was pinned next to a dead girl from his class, with her head next to his face.
"'I still see her sometimes," he said, speaking of his nightmares.
"I can't stop it all coming back.
"I still have nightmares and sometimes suffer from deep bouts of depression."
The horrendous aftermath was all the more painful to deal with given that there had been previous concerns from villagers.
A year before the tragedy unfolded, two mothers had presented a petition to Pantglas headmistress Ann Jennings about flooding - which she then passed on to the local council.
And in 1964, a local councillor - Gwyneth Williams - had said that if tip were to move suddenly it could threaten the whole school.
However, the warnings were ignored - and the fight for justice afterwards left many in the village feeling even more angry.
Despite an in-depth tribunal, which cited the disaster had been caused by a "bungling ineptitude" by the Coal Board, no one was ever punished.
And insult to injury was to follow when a protracted row over the cost of removing Tip Number Seven saw scared villagers, keen for the tragedy not to happen again, left little choice but to pay out £150,000 from a disaster fund .
The money was eventually repaid in 1997 - and the Welsh government went one step further 10 years on by donating £1.5 million to the Aberfan Memorial Charity.
But while time has healed some, but not all of the scars, the events of that day have not been forgotten in Wales.
On Friday, the Welsh Assembly will fly its flags at half mast as a mark of respect to those left devastated by the disaster.
And at 9.15am people will observe a minute's silence.
First Minister Carwyn Jones said: "The disaster in Aberfan was one of the darkest days in modern Welsh history and we remember the adults and school children who lost their lives.
"We also think about the survivors, those who lost loved ones and the people who answered the call to search and care for survivors, and recover those who had perished.
"Individuals, families and the community have been profoundly affected by the disaster.
"Half a century after, it is fitting that the country as a whole comes together, with respect and compassion, to remember."
Surviving Aberfan will be shown on BBC Four at 9pm on Thursday, October 20.