Miss Saigon has been an emotional rollercoaster, both on and off stage, for Miriam Valmores-Marasigan, who shares the starring role of Kim. She tells Viv Hardwick how ten years with the multi-million pound show almost cost her personal happiness.

Miriam Valmores-Marasigan doesn't just look and sound like Miss Saigon on stage - she's experienced some of the real-life world of her character Kim. Still only 26, and the mother of a small son, being part of the award-winning Boublil and Schonberg musical for ten years has almost cost her her marriage to childhood sweetheart, Itoy.

She's a Filipino and not Vietnamese, like Kim, but was plucked from an uncertain future at 16 in Manila's pressure-cooker atmosphere to join Australia's original cast of Miss Saigon, steadily progressing from ensemble to understudy to starring role.

Miriam says: "I'm playing a single mum in a war-torn country, but now I'm married and have my own son, Matthew, who is turning five this December and I've been away from home so many times... so I guess there's a lot more that I draw my emotions from."

Speaking about being part of a UK tour, which arrives at Sunderland's Empire Theatre in January, she adds: "I spend a lot of time away from Matthew so when I sing the song I Still Believe (about lost loved ones being together) it's real, it's hard. I'm pretty sure that the Lord prepared me for something as big as this - it's not easy playing Kim, not just vocally and mentally but much more emotionally. I've gone through so much craziness in the past few years, even though I'm young. Now I'm able to bring on stage what I'm bringing now.

"The early years of my marriage were really bad because I was always away from home so it was a tough time to salvage something. We almost broke up and I had a kid who was sometimes with me and sometimes not and it just broke my heart.

"Now we're really happy together again I can just see the big difference and I'm glad we made it through the bad years."

Itoy and Matthew are now living in Plymouth, where Cameron Macintosh's new touring version of the West End show started life in association with the Devon town's Theatre Royal. Miriam's husband, an IT expert, is applying for a work permit in the UK.

So many versions of Miss Saigon have gone out around the world since the West End show opened in 1989 that there is a steady demand for oriental-looking stars.

Miriam says of her big break: "I was in high school and my mom saw this ad in the newspaper and it was an open audition for Miss Saigon and she said 'this is it' and I said 'yeah right!'. I had never had any drama school training but had sung in church and school since I was three. There were thousands auditioning so it was an understatement to say I was intimidated and I was just quiet in the corner with my mommy while all the others were doing warming up exercises," she says.

But Miriam's one-song audition piece put her on the plane to Australia and within months, she was understudying the role of Kim - an orphaned Vietnamese girl who meets a war-weary GI just as poverty forces her to join the ranks of Saigon prostitutes.

She moved on to casts in London, Manila and the show's Asian tour before signing up for the two-year UK tour which arrives at Sunderland's Empire Theatre next year.

She says of show stardom: "The novelty has worn off a bit, but it's a big challenge - that's why there are two of us sharing the role because it's so demanding. It's just an honour to play a role that was originally performed by Lia Salonga, who is an international star.

"I didn't get that many chances to play Kim until the UK tour in 2002-3. I did dread it when my chance came because I was a lot more comfortable in the role before it became so huge. It was never really my first passion because I didn't have that crazy eagerness to get on stage. I was more hesitant to be in the limelight, but now it's a lot better.

"I actually made four attempts to go back to university, but Miss Saigon always got in the way. You grow to love it - now I don't feel wrong about performing, I love being on stage.

"Singing is my first love and I'm driving Steven Houghton (who plays her GI lover Chris) crazy because his dressing room is next to mine and I'm singing before and even after the show."

And the girl who has grown up as Miss Saigon adds: "Acting is an art that I've really learned to love. I don't know if I can do something else because I've never done any other show, but I'd love to try."

* Jon-Jon Briones, who has received rave reviews for his performance in Germany, Manila and the Asian Tour, plays The Engineer; Jennifer Hubilla, from the US Tour, shares the role of Kim.

* Miss Saigon runs at the Sunderland Empire from January 18 until March 5. Tickets: £14-£35.

Box Office: 0870 602 1130. Groups Sales: 0800 587 5007