CATHERINE JOHNSON'S modest terraced home was a long way away from Easy Street. "I had always held this dream that I was going to be a writer," she recalls.

"But by the time I reached 30 I suddenly realised I'd had two children - but I hadn't had anything published.

"I realised that if I didn't do it soon then I'd never do it. So I sat down at my typewriter, pushed away the coffee cups, shut my ears to the television, and wrote my first play."

The mother of two became reasonably successful, writing plays with real social resonance such as Rag Doll, which dealt with child abuse.

But while it provided her first break - it was performed at the Old Vic theatre in Bristol - life was still a struggle.

However, Catherine, now 41, persisted. During the day she worked in a record shop and at night she wrote.

Gradually her work gained her greater attention. She wrote for the Bush Theatre in West London where director Terry Johnson (no relation) was greatly impressed.

And although Catherine, from Bristol, didn't know it then, this was the moment that was to change her life.

Meanwhile, in another part of London, producer Judy Craymer had a dream.

"The story began 22 years ago when I first met Bjorn Ulvaeus and Benny Andersson, the song-writing geniuses behind Abba," says Judy.

"I was working for Tim Rice who was collaborating with Benny and Bjorn on the musical Chess.

"It was their song The Winner Takes It All that first suggested to me the potential of a musical using Benny and Bjorn's classic compositions.

"The lyrics tell a roller-coaster story of love and loss: it's extraordinarily theatrical."

Judy approached Benny and Bjorn, who were understandably unsure but left her with hope. But what to do with the songs? Nights were spent on the floor of her apartment listening to Abba records, searching for a way forward.

"I was driving my neighbours to despair," she says, grinning, "but I was more and more certain of my idea. And in 1995 my tenacity finally paid off.

"Bjorn said, If you can find the right writer and story, well let's see what happens'."

Judy searched high and low for a writer and a year later, Terry Johnson recommended Catherine.

"I was aware of her work and, even better, I knew her agent, " says Judy. "We met in January of 1997 and I was able to confidently tell Bjorn that we had found our writer."

At this point, single mum Catherine could barely afford a child minder so she could attend her first meeting with Andersson and Ulvaeus.

But although it went well, her remit was restricting. The story had to be a contemporary, ironic, romantic comedy.

And, like Abba's songs, it should appeal to two different generations.

She created Donna, an English fortysomething single mother who runs a bar on a Greek island.

Donna's daughter, Sophie, is planning her own wedding and wants to invite her father - but Donna is not sure which of three lovers is the right man, so Sophie asks all three to the wedding.

Judy knew it was a winner. "When Catherine had finished the first draft of a script," she says, "I persuaded Phyllida Lloyd to come on board as our director.

Her background was serious, legit theatre and opera. And her secret weapon was her dry Martini wit."

Judy adds: "It was unusual, if not unheard of, for three women to be the collaborative creative force behind what was to become such a commercial success.

"I think it had a great nurturing effect on the production.

"We were all happy to jump in and make the tea.

Appropriately, Mamma Mia! features three strong women in the story."

After what Judy describes as a white knuckle ride of hiring theatres and cast, on April 6 1999 - the anniversary of Abba winning the Eurovision Song Contest with Waterloo 25 years before - the world premiere of Mamma Mia! was staged in London.

The audience adored it - one critic wrote: "Mamma Mia! could put Prozac out of business."

Some critics have suggested the show doesn't know whether it's an all-out kitschfest of 70s nostalgia or a serious study of mother-daughter relationships, but that doesn't matter.

What does is that the story is strong enough to incorporate 23 songs including Money Money Money and Take A Chance On Me, without seeming as though they've been crowbarred in.

Now 17,000 people see the show around the world each night. And at the last count Catherine, who also wrote a musical based around the Bay City Rollers music, was tipped to collect £6million in royalties.

"The real security comes from knowing the kids will be looked after now," she says.