PIERCE Brosnan is a very good son. During the filming of the hotly anticipated Mamma Mia! sequel, he had a day off so decided to take his mum out to lunch. But as fate would have it, his phone rang to call him to set.
"I said to her, 'Well, Mum, you may as well come with me, we'll go to work' and we went down to the studio.' I had no idea why I was being called in, just to be part of the ensemble, I guessed," the Navan-born former James Bond says.
"And there was Cher. Everyone was there with their mothers and fathers and boyfriends and girlfriends – all watching her do her thing."
The US singing superstar is the newest and starriest addition to the cast as we return to the island of Kalokairi for Mamma Mia! Here We Go Again, 10 years after the first film was a box-office juggernaut.
Cher plays Ruby, the mother of Meryl Streep's character Donna Sheridan and appears in the film alongside returning stars Brosnan, Dame Julie Walters, Christine Baranski, Amanda Seyfried and Colin Firth.
"My mum sat there with Meryl and Christine and Julie and she was in heaven," Brosnan (65) remembers.
"It was a glorious day, a fabulous day. It was five takes with 300 people there, seven cameras. I filmed it too that day. I've got it on my camera, tucked away. It was a little bit surreal, but the air crackled with anticipation for her arrival, that's for sure.
"And she was so gracious with us all; she knew she was coming into a company of actors and she's a great actress herself."
Baranski, who returns as Tanya, laughs at the memory. "We were all watching, because she really is a rock chick. She's the real deal.
"Meryl turned to me at one point and said, 'So this is how it's really done'. But if anything she was rather shy about it and intimidated."
Indeed Cher herself admits she was petrified on her first day on set.
"I was terrified!" the 72-year-old confesses. "Everyone had been together and my character wasn't very liked so I was nervous, but everyone was nice to me.
"Meryl was behind a piece of scenery watching me do my number and that made me feel good after the fact but it was hard to go on a set where you were a stranger to everyone. I knew some of the people, but I am doing this 'mean grandmother' thing.
"But in the end, I felt really loved and kind of like a great grandmother."
Indeed nobody loved her more than Seyfried (32), who returns as Donna's daughter Sophie, and burst into tears when she found out Cher would be playing her grandmother.
"I was so intimidated and then I realised she was intimidated by me – and us. "And we were intimidated by her but I had to be the catalyst to be like, 'No no no, you are more than welcome and we love you' and after that everybody would go up to her because they realised she's amazing and sweet and it was fine.
"Now it's like, 'Why was she not in Mamma Mia I?'"
But even without Cher, it's hard to comprehend the success of that first Mamma Mia film in the UK, where it made almost £70 million.
When it was released in 2008, during the depths of the credit crunch, it became the highest grossing film of all time at the British box office. While it has since been usurped by a number of big-budget blockbusters which have pushed it down the rankings, it is still the most successful musical.
But despite that success, the cast were not optimistic they would get a chance to reunite.
"We had all but given up," Baranski (66) says. " Not that we were just waiting by the phone for 10 years, but we had so much fun the first time that we hoped that we could all just be together for the pleasure of the experience again.
"So when I heard everybody had agreed to do it, I just thought, 'Oh my gosh, how fabulous will this be?'"
Indeed, playing man-eating Tanya was light relief compared to her long-running role as Diana Lockhart in TV dramas The Good Wife and spin-off The Good Fight.
"It was such a pleasure to get away from the seriousness of that character and that show, and I love the show and I love the character, but skipping down a hill and singing Dancing Queen with Pierce is really refreshing. That change of pace!"
And luckily for Brosnan, his dancing shoes still fit.
"It was just as humiliating and embarrassing and just downright ridiculous," he chuckles. However, it's a case of anything for a laugh for the Meath man. "Those particular days with the big numbers were joyous because we were all together as a company, the young 'uns and us – we were known as the legacy cast."
Indeed, seeing so many major stars throw themselves into the musical numbers, with varying degrees of skill, is all part of the appeal.
"A lot of the secret, the charm of the movie, is seeing actors with real reputations just out there and kind of letting go," Baranski agrees.
"Our tongues are a little in our cheek and we know it and everybody knows it, but we're all having a ball. So I hope people in the audience will just go for the ride. They did the first time and I think they will the second time."
But for Seyfried, who had just given birth to her first child with husband Thomas Sadoski, she was caught unaware when she got the call.
"I was not mentally prepared for it at all. But then I read the script and I was like, 'I could totally be mentally prepared very soon for this'."
In fact it ended up being serendipitous, because the movie is so much about motherhood, and the relationships between mothers and daughters.
"That's why the timing was so perfect in the grand scheme of things," she says.
"I related to Sophie differently and it's so amazing that when I first saw the cut of the musical number I've Been Waiting For You, I was just floored because I know how much that meant to me because I am having a moment with my unborn child, as Sophie.
"It is cut together with Lily as Donna having Sophie and that relationship to this baby is blossoming on the screen and everything about that just runs so deep.
"It means so much more than it could have possibly had I not had a child."
:: Mamma Mia! Here We Go Again is in cinemas now
