Ash, Somerset House, London

The last time I saw a band play the courtyard of this quietly grand government building, birdsong could be heard over Lambchop's sunny, summer-evening strumming. Ash's eager power-punk, starting after darkness has fallen, doesn't exploit this odd, occasional venue with anything like that effect. As their red stage lights and stadium sound bounce off statues and stone walls, you quickly forget where you are. It's just another slightly underwhelming Ash gig.

When you form a band at 12, as the core duo Tim Wheeler and Mark Hamilton did, there's always going to be an adolescent element to your music, and it's to Ash's credit that they've yet to mature in any irritating way - they continue to pump out brilliant, punchy pop singles even now that Wheeler is all of 26. But the downside, whenever they have to fill 90 minutes of gig time instead of three perfect radio minutes, is that their songwriting has never really developed. The only distinction you can make is that some summery, harmonious thrashes are better than others. As Wheeler proved in an unwise acoustic slot supporting the Flaming Lips earlier this year, where his lyrics' paucity was exposed, Ash have no depth, hidden or otherwise.

But you can't fault them for effort. Playing their first headline gig for some while, with an album's worth of new songs that they're itching to test out, they bound and knee-bend round the stage with no thought for the night's soaring temperature, and the audience soon responds with old-school crowd-surfs and mass pogo-ing. The slow bass rumble, sweet harmonies and surging chorus of Ash's biggest hit, "Gold- finger", are dispensed with early on, but there is, of course, plenty more where that came from. By the story of adolescent summer romance in "Oh Yeah", even Ash's older, more sensible female fans are happily bouncing around me, and sweat is slicking the lean Wheeler's hair. He alludes to the near-career-finishing crisis after their flop second album Nu-Clear Sounds several times, introducing their 2001 comeback hit "Shining Light" by saying, "We wouldn't be here if it wasn't for this." He windmills at his guitar with appropriate, Pete Townshend-like urgency, and there's a feeling throughout that Ash are grateful to be playing at all.

But the quality of soft yearning that made "Shining Light" special is hard to locate elsewhere. The new songs that they play just sound like heavier versions of their old songs (the trick that made Nu-Clear Sounds crash). When they play "Jack Names the Planets", their innocently, completely infectious debut, released when they were still at school, Ash's arrested development is proven. They perfected their concept at the very start, and they now seem doomed to repeat it forever.