It is easy to see why Avril Lavigne was snapped up by a major label before she was old enough to drink at most of the venues she plays. At 17, she is the leader of a pack of earnest North American mini-Alanises (see also Michelle Branch and Vanessa Carlton) who aim to siphon fans away from the Britneys by writing their own songs and keeping it real.

But in Lavigne's case, realness is relative. She may co-write the tunes and wave an acoustic guitar during the encore, but her self-dubbed "skater chick" image bears the imprint of stylists, and her debut album, Let Go, was produced by Celine Dion's producer. To keep it really real, she would have to get rid of her N*Sync-a-like backing band, barricade herself in her bedroom and sulk till she is 21.

Still, such is the hunger for an alternative to Britney-schlock that Let Go made the American top five, and its single, Complicated, is big on Radio 1. But even a few of the fans - most female, 15 and clad in Lavigne-style striped neckties - had some reservations. As another feistily hormonal rocker jangled to a close, Charlotte from Staines observed: "Most of them sound the same, don't they?"

Yes, they did, with the exception of the Blondie-ish opening number Sk8er Boi, and Lavigne didn't have the presence to turn averagely angsty songs into something interesting. Still green enough to cry "You guys are fuckin' awesome!" at the merest ripple of applause, she was content to be bopping on stage in big sunglasses, the girl every girl in the house wanted to be.

With songs as unremarkable as these and a voice that's strong but flavourless, her lack of live experience worked against her. Though the likes of Unwanted grappled shoutily with the wretchedness of adolescence, Lavigne was just too, well, adolescent to carry a whole show on her own. Tellingly, the best moment was when she received a card from someone in the crowd. "It's Britney Spears crying," she giggled, abandoning the packaged skater persona and sounding, for a minute, as if she were enjoying herself.