A chance conversation between two men led to the revelation that one had saved the other's life when a tip above Aberfan in south Wales slid down the mountain and engulfed the village, killing 144, including 116 children.
Thirty-four years after the 1966 disaster, Jeff Edwards, one of the children to survive the disaster, was a local councillor in Aberfan, working alongside another councillor - a former fireman called Roy Thomas.
They were from different political parties, neither great friends nor foes. A chance remark one day led Roy to realise that more than 30 years on he was talking to the now grown-up boy he had pulled from the slurry that day.
"It was so emotional - I just couldn't believe it," said Roy. "It was lovely to come face to face with the boy I had saved."
Jeff was the last to be pulled out alive from his classroom in Pantglas Junior School. The only thing that had saved him was Mr Thomas spotting a mop of his bright white hair sticking out through the dark mass of coal waste.
Only four children out of 34 from Jeff's class survived. At first he found it painful to come back to the village, staying instead with his grandmother a few miles away.
Roy Thomas and Jeff Edwards were reunited after a chance conversation
"I was too frightened. I lived in fear of the tips coming down again," he said.
He later moved away to London to work and qualify. But 12 years ago he felt an overwhelming urge to return and found Aberfan, like many communities in south Wales, was facing social problems.
Drug-taking had become a serous problem along with car crime and burglaries.
"Aberfan post-disaster faced big problems. The colliery closure for one brought unemployment of 28%. I came back and saw the social problems in the village and just had to do something," said Mr Edwards.
"Since then I've tried to devote most of my life to helping youngsters."
Disturbed by the problems he saw, he was a driving force in the creation of the Aberfan and Merthyr Vale youth community project - a scheme to help people in the village help themselves.
One of the major problems was unemployment. Many who found jobs outside the village had no car and no means to get to work.
Jeff Edwards - in 1966 and 40 years on
Others had difficulties with child care, some needed to gain basic skills or retraining after a life dependent on coal. A crèche was opened offering favourable rates, youngsters were lent cars so they could first get to work. Training schemes were set up.
A cyber café opened up in the heart of the village offering computer access and training. Literacy schemes were introduced to improve people's self-esteem and motivation.
It was the start of a scheme which now has dozens of projects which bring new life to the village - and ironically is probably the village's biggest employer, with 50 people on the books.
In fact it's become one of, if not the, leading regeneration programme in the UK - a blueprint that is now copied throughout the country.
For Mr Edwards, it has been a cathartic process - he's gone on to hold many prominent positions in life. Recently awarded an MBE, he's been mayor of the town and is chairman of the local magistrates' bench.
A recent trip has taken him to Uganda to try to help an impoverished community there.
At the time of Aberfan, post-traumatic stress wasn't recognised. He now travels the country helping advise others on how to cope with disasters and their aftermath.
The scheme, now run by a new group of local people, has helped hundreds more.
Gareth Jones was one of the first children brought out alive from Pantglas Junior that day.
A few years ago he had an accident. The injuries meant he could no longer work as a lorry driver and he became depressed. One day he wandered into the cybercafé just a few doors away.
"I'd never even switched on a computer before - but I was fascinated and they taught me how to work with them," said Mr Jones.
That was the inspiration he needed. He soon gained the confidence to set up and run his own business, designing and building websites.
"It's changed my life around. I never thought I would have my own business, and a successful one at that that gives me a good income," he said.
For the parents the struggle to come to terms over the last 40 years has been a deep and private one.
Cledwyn Davies lost his son Gareth in the disaster.
"Immediately following the disaster the village sunk to a terrible state. The grief was unbelievable," said Mr Davies.
"Everyone was grieving for those they'd lost .There was a wave of anger - why did this happen - why was it allowed to happen? At the time we just didn't know if we would ever get over it.
"But being a Welsh valleys community, we were resilient. After a period we thought we must start getting over this. Clubs and groups starting springing up."
The village choir acts as an ambassador for Aberfan
Mr Davies became chairman of the community association and also threw his energies into getting the tip removed . Once that battle was won there seemed to be a void.
But then came an idea that was to bring the families together, and still does to this very day. People from the tip committee and others affected in the village started getting together to sing, and soon the Ynysowen male voice choir was formed.
"It helped tremendously in our recovery," says Mr Davies.
The choir now meets regularly and tours the country for concerts, acting as an ambassador for Aberfan.
For Jeff Edwards the healing process isn't complete, and probably won't ever be.
"Some days I get up look at myself in the mirror and just can't face what I see," he says. "On days like that I have to just go back to bed and give in.
"I am unable to shave - I look in the mirror and the depression is quite deep. I've learned to cope. But many haven't and they turned to drinks and drugs."
Mr Edwards said the chance encounter with Mr Thomas - meeting his rescuer - at least helped him move on.
Forty years on Aberfan is giving thanks for the lives that were saved, and the brave men who struggled to bring them out alive. It is remembering those who were lost and those who lost. It is also rebuilding a future.