Though he doesn't like to dwell on the Aberfan disaster, Philip Thomas can still recall with great clarity the events that saw him buried alive but survive 50 years ago today - and the chance request that saved his life.

Being chosen at random by his headmistress to help his classmate Robert pay off a dinner money debt was what ultimately stopped him from being mourned along with the 116 children and 28 adults who died on October 21, 1966 in the Welsh village.

"I was asked to go down to the senior school with Robert to collect dinner money from his sister that he was owing," Philip recounted to ITV News Wales Correspondent Rupert Evelyn.

"So me and him set off that morning ... and we were talking to some children on the wall of the senior school. We were down on the road, on the pavement.

"We could hear a rumbling noise, a bulldozer or a train or something rumbling, then it was like someone was throwing stones from the canal bank.

"And we just run. But whatever hit me then ... hit me on the head ... and then I went down with my hands on the back of my head.

"I just woke up in a black - pitch black. Then I just started shouting and crying for my mother. I could hear voices then saying 'there's someone here, there's someone here.'"

Philip was dug out by firemen and rushed to hospital.

It took his parents hours to learn he was still alive, one of three survivors from a class of 32 after 150,000 tonnes of coal mining slurry hit Pantglas Junior School. His classmate Robert did not survive.

"I was lucky," Philip said. "Poor Robert wasn't but I was lucky."

Philip suffered serious head and leg injuries, a ruptured spleen and a fractured pelvis, and needed surgery to reattach an ear.

Most life-affecting was losing three fingers from his right hand - though because of memory loss brought on by the accident Philip said he can't remember ever having them.

Philip Thomas lost three fingers in the accident.

The schoolboy said he was encouraged to move on from the disaster by a mother who "would never speak about it".

In adulthood he would move away from the area, which he said stopped him having to recall the disaster whenever people asked where he was from.

"I didn't have to go through saying that I lived or went through Aberfan," he explained.

Philip said he doesn't feel inextricably linked with the tragedy.

"It affected me and it hasn't affected me," he said. "I've had a good life after the disaster. I've never dwelt on it."

A few months before today's 50th anniversary of the disaster he did experience a "very emotional" connection to the day, meeting two of the firemen who dug him out of the coal slide.

The graves of the victims of the Aberfan disaster are held under arches in the village's cemetery in Wales. Credit: PA

"I found it very hard to stop the tears," Philip said. "But it was nice to meet the two gentlemen, Len and Dave."

He said the anniversaries and visits to the Aberfan memorial site do make him pause to reflect on the day he survived while so many others didn't.

"I do think a lot on the anniversaries of children that didn't survive and it is sad," he said.

"I go up to (visit the graves of my) mum and dad in the cemetery. The odd times we go up I'll have a walk around the (memorial) arches and it brings little memories back of the ones who were in my class. So yeah, anniversaries are hard."