The 59-year-old singer’s uncle was among those who went to help on that day in October 1966, when an avalanche of coal waste engulfed a primary school in the village, near Merthyr Tydfil killing 116 children and 28 adults.
But what really brought it alive for the Bromsgrove-born star – whose mother was born in the Rhondda valley, where his grandfather was a coal miner – was an episode of Netflix drama The Crown, which details how the royal family responded to it.
When it came to filming his new Channel 5 documentary, Wonderful Wales With Michael Ball, he decided he wanted to visit and pay his respects – and it makes for incredibly moving telly, as we see him meet survivors too.
“You have the Memorial Garden – which is on the site of where the school was – and right next door is a playground for the kids,” recalls the charismatic star, who’s famous for his performances in West End productions such as Les Miserables, Sweeney Todd and The Phantom Of The Opera.
“It was half term, and all these kids were playing in it, and so you could hear the sounds of kids laughing and enjoying themselves. And it just struck me; those kids, another generation, and they would have been there.”
He adds: “The actual gravesite itself was amazing. It’s done with such dignity, love and respect.”
In the four-part series, the world-famous performer – whose long-term partner is broadcaster and journalist Cathy McGowan – explores valleys, mountains, and coastlines.
Along the way, he discovers the country’s traditions, history and culture, while also sharing his own Welsh ancestry.
We learn about his grandmother – who was an inspiration for his singing career – as he returns to where she lived, in Cadwaladr Street in the village of Mountain Ash.
“She was a real central character within the community,” he gushes. “She was the one who organised things, the one you went to when you had a problem, the one you would have a laugh with.
“She recognised, from an early age, my love of performing – and she always encouraged me to do that. It was never, ‘Oh, sit down, be seen and not heard’; she would push us forward.”
Sadly, his gran passed away a week before his big break, which was a production of The Pirates Of Penzance at the Opera House, Manchester, in 1985.
“That broke my heart. She was a phenomenon – Welsh women are! It’s a matriarchal society. It was the women who ran – and still do run – the households, and who are the disciplinarians and comforters. They breed them strong in Wales. My mum’s the same.”
The chat with Ball takes place on Zoom, during a break from rehearsals for Hairspray at the London Coliseum.
This summer sees him reprising his Olivier Award-winning role as Edna Turnblad, a character he says he has totally based on his gran.
“When I first did it, 12, 13 years ago, my mam and my sister and family all came [to watch]. They burst into tears, because I was Gran; that’s who I modelled the whole physicality on.
“When I’m playing Edna, I wear my gran’s perfume on stage, so I smell like her. Madame Rochas; it’s a lovely smell. I always do that with every character I play, they have their own smells. The last thing I do before going on stage is cover myself in that.”
What’s particularly lovely about Wonderful Wales With Michael Ball is that each episode finishes with him singing with a different local choir across Wales – each of whom hadn’t been able to sing together during the pandemic.
“They tried to do rehearsals on Zoom, but it’s not the same,” he notes. “We were always outside, and always distanced, but being in the gang and hearing that wall of sound – it was very emotional for all of us.”
This was especially the case when filming in Portmeirion in April, where one of the singers he met is a doctor and mum-of-two, whose 36-year-old husband – a “young, fit, healthy, rugby-playing lad” – had been suddenly rushed into hospital in the February.
“They said, ‘We think he’ll probably come home to you tomorrow’. And then he developed blood clots from Covid, and he died. It was devastating, for everybody; obviously for her and the family, but for us hearing the story and the choir, who’d got round her.
“It was incredibly powerful and moving. And kudos to her for coming up and being able to talk about it. That was amazing.”
Ball had Covid-19 at the start of the pandemic, back in March 2020, and he says he realises how lucky he is to have recovered from it.
“I was really poorly, but not as bad as Cath,” he confides. “I was juggling that whole thing of, ‘Do I need to get someone in to intervene, or can I manage this myself and keep her at home?’ Which I did – and I’m glad I did.”
He follows hopefully: “Having had it and having been double jabbed, you kind of feel, ‘Take me out there. I’m ready to go out onto that stage!”
Has he found himself dealing with any symptoms of long Covid?
“I don’t think so; Cath is unsure. She has days where she literally just wants to sit down and fall asleep. They’re getting fewer and fewer. But [we’ve had] none of the really extreme effects that a lot of people have.
“When I was in Les Miserables, I had glandular fever, which led to ‘post-viral syndrome’, they call it; they used to call it ‘yuppie flu’, back in the day. So, I do understand, and I do sympathise. But touch wood, I’m OK.”
With restrictions on travel still in place because of the pandemic, many of us are looking at holidaying closer to home this year.
And Ball hopes this new series will help people see that “there are so many layers to the Welsh landscape, to the Welsh people, to the Welsh heritage, to just dive into”.
“It’s a joy of a place and it’s on our doorstep – don’t miss out on it,” he follows, grinning.
“Because there aren’t many places like it in the world, and we should be really proud of it.”
Wonderful Wales With Michael Ball starts on Friday, July 9.