Catherine Feeny is mad, bad and dangerous to know. Well, perhaps not, but touring with Kelly Jones of the Stereophonics has definitely brought this demure American songstress out of her shell. The turning point came during a gig at Vicar Street in Dublin, where an unusually rowdy section of the crowd started laughing in the middle of one of her songs.

"I just felt like I couldn’t take any more. I felt so enraged that these people were being so disrespectful. So I just stopped the song and said, 'That's a bit FUCKING RUDE!' I'd never done anything like that before in my life but I felt I'd be such a doormat if I just let this happen and didn't do anything about it. The audience actually loved it – they started clapping."

She has good reason for this newfound assertiveness. Her irresistible ballad 'Mr Blue' attracted over 20,000 downloads after appearing on the soundtrack to 'The O.C.', and now the 29 year-old has been signed to EMI subsidiary Charisma. Next week sees the release of a remixed and repackaged 'Hurricane Glass', the album of melancholic folk-pop she originally put out last year.

Success and self-confidence have taken their time to come Feeny's way. Born in Pennsylvania, she worked as a journalist in Washington D.C. before moving to Los Angeles, where she wrote about visual effects for a movie trade webzine. She gained a small fanbase playing in LA but little in the way of record company interest. Then she met musician and producer Sebastian Rogers, who enticed her to his studio in the village of Winfarthing in Norfolk to record 'Hurricane Glass'.

You might think East Anglia would be the last place to go to galvanize your music career but abandoning the hubbub of LA for the English countryside seems to have done just the trick. So much so, in fact, that she's now permanently based in Norfolk. "I know it seems quite strange," she laughs, "but it just kind of made sense to be here."

Clearly the collaboration with Rogers has been vital to her, not least for helping her rediscover her pop sensibilities. "I always had been into pop music but I'd gotten into a really folky scene in Los Angeles. I'd forgotten that I actually like full production values, that I actually like Tracey Chapman and Sheryl Crow albums that are full-on pop. I was coming from much more of a Gillian Welch aesthetic."

And like some of her role models she's not shy of mixing chart accessibility with political engagement. Amid her album's lovelorn balladry is the deceptive lullaby lilt of 'Unsteady Ground', in which a government soothes its public into dozy compliance with the atrocities it commits – "the children don't know yet that we're bombing Baghdad". Sure enough, Iraq is a subject that also arouses her ire:

"When the whole WMD controversy was going on, the thing that was frustrating for me was – yes, the Government was lying to us, yes, the press was letting us down by just being a puppet of the Government, but people were eating it up and I just couldn't understand it! It was so clearly a scheme, we were so clearly being manipulated."

Of course Feeny is aware that like many well-meaning musicians before her she's treading a fine line between preachiness and cliché, but she remains unapologetic: "I do feel the artist that I want to be is someone who's aware of what's going on in the world and is not afraid to express their opinions."

Catherine Feeny will be playing the acoustic stage at Glastonbury on 23rd June. If you want to stay the right side of her, don't mention the war and don't, whatever you do, talk over her set.

Single 'Touch Back Down' 11th June
Album 'Hurricane Glass' 18th June