Kate Nash, Village Undergound, London

Skin-tight black lycra catsuit, severe fringed bob and jet-black eye shadow, all finished with a cropped leather biker jacket and shoulder pads. Kate Nash's new look certainly matches the scenester setting – an intimate converted warehouse tucked down a Hoxton backstreet. But as first impressions go, the crowd seem miffed. There's a dour-faced dominatrix sitting centre stage behind the keyboard, where a smiling frock-clad girl-next-door used to be.

Having famously conquered the hearts of angsty teenage girls with her 2007 debut album, Made of Bricks, Nash's magic lay in her fluctuating north London accent, youthful ability to make the ordinary poetic, and talent for penning catchy pop with substance.

However, word on the wavelengths is that the 22-year-old's newest offering, My Best Friend Is You (released last week), attempts to prove that she is now a bona fide grown-up woman, with a proper band, and some serious music to boot.

But it's a very ordinary performance indeed until, finally, the mood drastically transforms. Nash sweetly shushes the crowd before beginning the understatedly powerful new track "I Hate Seagulls", possibly inspired by her beau, Cribs singer Ryan Jarman. This is Nash stripped bare – just elegant vocals and her guitar – and it's a triumph. The crowd are moved and deliver the biggest cheer so far.

Nash declares that the next song is about homophobia, which sets the fans off in a pre-emptive applause for the simple yet intriguing "I've Got a Secret". "No, no, no!" Nash objects. "You don't 'woo' homophobia, you boo it," she says in her best teacher voice, before launching into a performance that mildly nods to the dynamic feminism of Yeah Yeah Yeahs frontwoman Karen O. Following with the anthemic "Foundations", Nash has thankfully forgotten to be cool or didactic and the crowd seem relieved. She's smiling, laughing, pounding the keys skilfully, and she's on a roll.