Valentina Montoya Martinez had to pinch herself to make sure she wasn't dreaming.

In a taxi on the way to a concert in Glasgow she was singing with two members of Chilean folk legends Quilapayun and was about to perform the same song onstage with them.

For a British pop music fan, she says, this would be the equivalent of getting to play with the Beatles.

Martinez and Quilapayun had met before. As a 13-year-old, she had gone backstage at a concert they'd played in Birmingham and confidently told the group's guitarist and composer Patricio Wang she was going to be a singer. Wang remembered and in Glasgow was pleased to see she had realised her ambition.

"I always sang," says Martinez. "I can remember at home in Chile when I was very small, the little girl next-door and I, we were best friends, used to play these games where we'd improvise a microphone and take turns singing. Then when one of us felt the other had been using the microphone too long, we'd get annoyed and take it back, just playing, we were only having fun."

That's one of the better memories she has of Santiago. After the Pinochet regime took over in 1973, many were forced to leave the country, the young Martinez and her mother and older sister among them. In 1977 they headed for London, leaving Martinez's father behind. A civil servant, he had been thrown into a prison camp. He was later released to spend his days dressed for work but sitting under a tree at the bottom of the garden.

"Music became a comfort after we moved to London and then Birmingham," she says. "My mother had brought lots of recordings of Chilean music, so I grew up in England with the same soundtrack I'd known in Santiago. She was very insistent we spoke Spanish at home, which I resented at the time because I didn't want to be different from the other children.

"I'm glad now she did because it kept me connected to Chile. None of us thought we'd be away for more than a year or two but it was 1991 before we were able to return."

By this time Martinez was on her way to gaining a degree in Comparative American Studies at Warwick University. She went on to teach English and drama in Mexico for two years and once back in the UK, she took a masters degree on the work of inspirational Chilean theatre director, poet and songwriter Victor Jara. Then, having heard so much about the Fringe, she came up to Edinburgh for the festival in 1996 and stayed.

"I met my partner, David, who is a guitarist and sound engineer, when we did some work with a kora player and he started arranging the songs I'd been writing," she says. "That was the beginning of our group, Valentina and Voces Del Sur and that's allowed me to celebrate my roots because for a long time Chile was a source of pain, with memories of tanks and machine guns. Now I've been back and seen a lot that's familiar, I still feel some sadness but I can appreciate the good memories too."

As well as fronting Valentina and Voces Del Sur, Martinez has formed a strong working relationship with Mr McFall's Chamber, the definitive chamber music without frontiers ensemble, in whose production of Astor Piazzolla's tango opera Maria de Buenos Aires she takes the leading role this week.

"Some people might think it odd that a Chilean is playing this very Argentinean personality, the personification of tango, because there's a kind of love-hate relationship between Argentina and Chile," she says.

"But the two countries share much more in common than divides them and I think we have to stop thinking about borders and hatred and start sharing the world's limited resources for the children of the future.

"Besides, I can relate to the character of Maria, not just because it's moving and tragic, but because she gets some great songs to sing, healing songs. It's a sad story but also uplifting."

Valentina Montoya Martinez appears with Mr McFall's Chamber at Queen's Hall, Edinburgh, tomorrow and in Tango at the Cottier presentation at Cottiers, Glasgow, on June 12.