Wainwright on the night

Just when you'd expect her to be unleashing her eagerly anticipated second album on the world, up pops Martha Wainwright performing onstage with the Royal Ballet. It looks like brother Rufus hasn't got things all his own way when it comes to surprise career moves.

'It was Covent Garden, it was ballet and it was Kurt Weill - to me it was an obvious yes,' says Wainwright of Seven Deadly Sins, choreographer Will Tuckett's new version of a neglected Brecht and Weill creation. 'And I think I was really excited to get my head out of my own ass.'

Wainwright is referring to the claustrophobic obsession that can surround making an album, particularly one as critically acclaimed as her 2005 self-titled debut.

The new record is, she says, three-quarters done and an 'angry and disjointed', rockier move away from the folk-flecked style of the first. But for now it's on the backburner and ballet is the name of the game.

It's proving a sharp learning curve. In Seven Deadly Sins, Wainwright sings the role of Anna I, one half of a split personality, with the dancer half of the equation, Anna II, performed by the Royal Ballet's Zenaida Yanowsky. But Wainwright, who confesses that she did the little-girl-ballet-class thing, was intent that she wasn't going to stand still on stage.

'The first thing I asked was that I've got to do some movement, so Will took my request to heart. But, after the start of rehearsals, I thought my brain was exploding - you'd think you'd be able to remember how to walk across stage and keep on time, but there seemed to be so many things going on in my head.'

Part of that was the task of learning a set of unfamiliar, typically complex Weill songs. Though she's a Weill fan - she sang some of the 1920s German composer's pieces at last year's Meltdown Festival, which led to Tuckett wanting her for the part - Seven Deadly Sins, a torrid tale of sexual exploitation, is a relatively obscure work.

'This production is focused on the darker elements - you do see a rape - and it really is quite subversive. I'm finding my way into interpreting Anna - but I'm not an opera singer, I have an emotive way with a song. It brings something different.'

With Rufus at the Palladium paying tribute to Judy Garland and now Martha at the Royal Opera House, it's proving a flamboyant year, even by Wainwright standards. 'You could say that,' she chuckles, 'but we're both always trying to do something different. I guess we're trying to one-up ourselves.'

Seven Deadly Sins opens tomorrow as part of a triple bill also featuring Pierrot Lunaire and La Fin du Jour. Tomorrow and in rep until May 9, Royal Opera House, Bow Street WC2, 7.30pm, Apr 28 mat 2.30pm, £4 to £50. Tel: 020 7304 4000. www.royalopera.org Tube: Covent Garden