SHALL we re-run those stats one more time? At the last head-count, Mamma Mia! has been seen by 60 million people worldwide.

There have been 50 productions of the show fashioned from the ABBA songbook. It has been seen in 16 different languages (including Swedish). Plus, of course, there was the massively successful movie starring Meryl Streep.

And yet for all its 19 years trotting around the globe, Mamma Mia! has never once toured the UK. Until now. Why is that?

“Partly the success of the show in London,” explains the show’s producer Judy Craymer. “When we opened I asked someone’s advice about what should I be doing re. a UK tour. They said, ‘Watch your midweek matinee because when that begins to go soft then you should think about touring. It never did go soft."

Instead the show went to Canada and Australia, then toured the US and took up residence in Las Vegas before landing on Broadway the month after 9/11. It stayed for a dozen years. More recent conquests have been of China in Mandarin, while a vast cruise ship tours the Caribbean with a Mamma Mia! that can be seen by 1000 seafarers at a go.

Craymer has seen the show on every continent but has yet to be lured aboard the Royal Caribbean. “I was asked when they did the technical rehearsal between Hamburg and the Solent in November,” she recalls wryly.

Craymer is one of the least demonstrative super-producers on either side of the Atlantic. Hers is the only mega-musical to have proved itself unstoppable without any assistance from anyone called Lloyd Webber or Mackintosh or Nunn or be affiliated in any way to Disney or any other film franchise. Or indeed get any help from men at all (unless you thank Bjorn and Benny for the music). The three queens of Mamma Mia!, aside from Craymer, are director Phyllida Lloyd and book writer Catherine Johnson.

The show has been going since 1999, but its producer first had the idea for a film or a stage show based on Abba’s songs many years earlier when she was Tim Rice’s assistant on Chess, the musical he wrote with Bjorn Ulvaeus and Benny Andersson. “I started talking to them about it in the mid-80s, and then in about 1995 Bjorn said, ‘If you can get the right story, maybe.’”

By then she had worked as a producer in television and come across Johnson, a scriptwriter who had also written a couple of sparky hit plays. One of them was Shang-a-Lang, about three women from Chipping Sodbury who hit 40 in a holiday camp where their girlhood idols the Bay City Rollers are playing.

“I explained my thoughts and Catherine said, “What about a mother-daughter story?” and that was it. We tentatively pitched it to Bjorn and Benny and it kind of worked from there. They trusted me. They weren’t saying, ‘Bring in a star team. We’ll only do it with Tom Stoppard and Hal Prince.’ They let us nurture it. I think timing was everything. It probably wouldn’t have worked ten years before in the same way.”

Craymer is resistant to the idea that Mamma Mia! is just another jukebox musical. “To me those songs were written by Bjorn and Benny for Mamma Mia!” In fact they were increasingly written about their own failing marriages to the band’s two singers, Agnetha Fältskog and Anni-Frid Lyngstad. “’The Winners Takes It All’ was the inspiration for me. I kept thinking, that is a great 11 o’clock number, as they say on Broadway. It’s ‘Don’t Cry for Me, Argentina’. But what’s the story?”

The story centres on the search for a father. Twenty-year-old bride-to-be Sophie has grown up on a Greek island where her mother Donna runs a rackety taverna. Sophie doesn’t know who her father is, so rummages through her mother’s diary from twenty years back and secretly invites three potential candidates. As a feel-good plot it is a long way from the doom-laden blockbuster musicals which dominated in the 1980s and 1990s and Craymer thinks that helps explain its longevity.

“The show has a big heart and people love it so they return. In the audience sometimes one member will turn to the other and say, ‘Is this your first time?’ It’s like ‘welcome to the club’. It’s also a show that people like to see in a community atmosphere. They like to bring friends and family. Kids are brought up on the DVD of the movie and now’s their chance to see the show.”

The film – which also starred Julie Walters, Colin Firth and Pierce Brosnan - came out in 2008. At the time it felt like a final frontier for the show and Craymer looked about for alternative inspiration. It came in the idea of doing a Spice Girls musical. Viva Forever!, with a book written by Jennifer Saunders, opened in the West End in 2012. Alas it did not live up to its title and closed after six months.

“Although I do think it had potential’ she concedes, ‘there’s all kinds of reasons why it didn’t work, but I was very proud of it.” One thing that has changed is the power of social media to make or break a show. Mamma Mia! had good reviews but it mainly conquered the world by word of mouth – and, of course, wonderful songs. The show’s creators had no real idea how deep those songs are in all our bloodstream until they first launched them upon an audience.

“They stood up and cheered at the end and everybody was dancing. Somebody said to me, ‘This is just the first preview audience. Don’t expect this to happen again.’” People have been dancing at the end of the show ever since to “Waterloo” and “Dancing Queen”, sung by Donna and the Dynamos in wonderful Seventies spandex outfits. One night the audience proved so immovable that the front of house staff had to make an announcement that ‘the Dynamos had left the building’ otherwise the audience would have stayed all night. On another occasion they were joined onstage by Anna-Frid Lyngstad. “Frida came quietly one night, she wanted no fuss. She loved the show so much that she asked if she could go onstage at the end with cast, she did and she sang ‘Dancing Queen’ in front of the audience. And that was her quiet night out’.

In the mean time there just may be another twist in the Mamma Mia! story in the shape of a second film. “I think it would be a companion piece. It would only happen if we all agreed it was the right thing. People love that film and those characters and love being in that moment of escapism on the Greek island. It’s good for us to always be thinking.”