Prince William, King Charles and Queen Camilla will make a rare public appearance together this week to mark the 60th anniversary of the Aberfan disaster

Her absence in the aftermath of the tragedy was one of the greatest regrets of Queen Elizabeth's reign.

Now the King, Queen Camilla and the Prince of Wales are coming together for a rare joint public engagement to mark the 60th anniversary of the Aberfan disaster, which claimed the lives of 116 schoolchildren and 28 adults.

The royals, the Mail can reveal, will travel to the small South Wales village next week to pay their respects to the 144 victims of the worst mining disaster in British history, and the community that has sought over the last six decades to heal.

They will visit on October 21, 60 years to the day a vast colliery waste tip collapsed onto Pantglas Junior School and neighbouring houses with such devastating loss of life.

The avalanche of black slurry, which had been dumped on the hillside above the village, consumed everything in its path, including the classrooms at Pantglas which were packed with children excited for half-term, which began the next day.

Such was the extent of the devastation that entire streets in the village found themselves without a single child left.

There will be a particularly poignant moment for King Charles, who has asked to meet a schoolboy pictured with his late father, Prince Philip, the day after the tragedy.

Gareth Jones was just six when the Duke of Edinburgh visited the village.

A haunting black and white photograph of the day shows the clearly shellshocked young boy – who was saved after he was pulled out of a classroom window by a school caretaker, who tragically lost two of his own sons in the accident - meeting the Queen's husband.

In an almost unbelievable turn of good fortune, his sister Janice, then 11, and brother Graham, seven, all survived too.

Now aged 66, Mr Jones' memories of the horror remain sharp.

'The King knows about the photograph of his father at my house and asked about the children in the picture - one of the little boys is me,' he told the Mail.

'I remember a man coming to visit and we all came out the house to see him - I thought he was the king because he was the Queen's husband.

'He stopped to talk and said: "All three of you survived the disaster?"'

The photograph shows his mother, Rene, the three youngsters and Gareth's grandfather, retired miner and lay preacher Robert Davies, in the front garden of his tiny home.

The children had moved in with their grandparents because their own home in the village, near Merthyr Tydfil, suffered damage when 150,000 tonnes of coal slurry hit the school at 9.13am.

The picture has hung in Gareth's living room in Aberfan ever since - but he will take it off the wall to show King Charles and Queen Camilla when they also visit Cardiff to officially open the Senedd, the Welsh Parliament, this week.

Mr Jones says: 'The photo has always been special to me but it also has meaning for the King because his father is in it.

'If you look at it closely you can see there are no other children in the picture, they'd all been lost in that horrible day.'

The father-of-three, who has lived all his life in Aberfan, has been in hospital with a serious lung condition for the last six weeks.

But he was discharged last week, just in time for the royal visit and is working on his fitness, as he is so determined to stand for the royal meeting, although his children have bought him a wheelchair just in case.

He said: 'I'll be there whatever happens, I'm looking forward to telling the king my recollections of the day his father came to the village.

'The Royal Family have never forgotten what happened here, they have visited so many times.'

There was fierce criticism back in October 1966 when the late Queen chose not to visit Aberfan until eight days after the disaster.

While Prince Philip and Prime Minister Harold Wilson visited the site the day after the tragedy, Elizabeth, acting on advice from her private secretary, Lord Charteris, stayed away believing her presence would hamper rescue efforts and overshadow the grief of the family.

Lord Charteris later admitted it was a mistake, and the Queen herself came to view the delay as one of the biggest mistakes of her reign.

When she did visit, journalists - including the late Brian Hoey writing for the Daily Mail - noted that Elizabeth seemed unusually emotional and shaken by the grief of the families she met. There has long been debate as to whether it was one of the rare moments she wept in public.

Marilyn Brown, whose daughter Janette, 10, was killed said at the time: 'You could see she was quite emotional. You could see that she cared, you know.'

The youngest of her four children, Prince Edward, was just two at the time.

The story of the Queen's regret over Aberfan was brought to a modern audience more recently when it featured in season three of The Crown.

But Mr Jones bears the late monarch no ill-will, saying: 'To me, she held back as a mark of respect to the families who lost children. The Queen waited for the dust to settle, I still think it was the right thing to do. She was showing respect to the people of Aberfan.'

He met the Queen when he was 14 at the official opening of the Aberfan Memorial Garden in 1974 and now gives talks to local schools about the disaster and his incredible escape.

Speaking of that moment he recalled how he was pushed through an open window into the arms of school caretaker Stephen Andrews, who lost two sons in the disaster.

'He told me to run home and that's what I did. It's a miracle my brother and sister got out too,' he said.

Poignantly, the retired web designer was giving a talk earlier this year when he discovered one of the children was the great-great grandson of the caretaker who helped him to safety.

And that same child will present a posy to the King and Queen when they are in Cardiff this week.

It is rare for the three senior royals to conduct a public engagement together and is an insight into the legacy the disaster still has today for the royal family.

A palace source said: 'Their attendance reflects the longstanding connection the royal family has made with the people of Aberfan over many decades.

'This will be an opportunity for them to pay their respects to those who lost their lives, and hear the inspiring stories of how this community rallied to support one another as they face the most unimaginable tragedy.'