Supergrass, Somerset House, London

Instead of three-minute pop gems, Road to Rouen consists of instrumental excursions, odd turnings and the most muso of instruments, the zither. An upcoming acoustic tour aims to further emphasise their credibility. In interviews, singer, Gaz Coombes, has hinted that the album follows a couple of difficult years for the group, what with his fatherhood and the drummer Danny Goffey's outing by the tabloids as a swinger in the Primrose Hill set. Yet Supergrass are nothing if not reliable.

They have long been a festival draw thanks to their cache of greatest hits, and they rose to the occasion in Somerset House's imposing courtyard with a selection of hits that took in a broad sweep of their career to date. The strangled yelp of "Strange Ones" harked back to the band's early days, while the twitchy funk of last year's "Kiss of Life" was just as powerful and showed they had not lost their touch. They played with exemplary precision as Mick Quinn's rock-solid bass was brought to the fore.

But despite the vibrancy of their tunes, the group had all the character of a Volvo estate. Coombes's crowd interaction ventured no further than saying "thank you" in a transatlantic accent that was even more Marc Bolan than his singing voice. The shy Quinn, meanwhile, preferred to face the drummer and hid behind a curtain of hair when he ventured forward to sing harmonies. The keyboards of Gaz's brother Rob gave added texture to the fragile "Moving", yet his stage presence was even more negligible. You soon understood why "Alright" was such a bad fit.

A spry "Sun Hits the Sky" was further enlivened by a percussionist, whose congo outro was ineffectual in the face of Goffey's pneumatic drill delivery. Then the singer and Quinn assumed sedentary positions to showcase the new material, with even Goffey settling behind a pint-sized drum kit. Now would have been an ideal time to introduce unfamiliar songs to the audience, yet Coombes treated them with the same insouciance as the rest of the set. Maybe it would not have mattered if Road to Rouen were as hook-laden as their best work, but as the pedestrian strum of the single "St Petersburg" plodded on, it was clear that Supergrass had forgotten that vital ingredient.

Even worse, the band had lost their short attention spans. Previously, they had nicked liberally from disparate, if obvious sources. A bit of mod here, a chunk of blues rock there, but bare-faced cheek and punkish urgency made it forgivable. Now in thrall to Jimmy Page's progressive tendencies, rather than his filthy riffs, the songs meandered rather than punched home.

"Tales of Endurance" only held interest as Quinn and Coombes changed instruments mid-song, the sulky line "Welcome commercial suicide" emerging as a self-fulfilling prophecy. The album's title track caught the ear with its vibrant blue-eyed soul, but then "Low C" sounded more like a B flat. The band's take on Gil Scott Heron's "Lady Day And (John Coltrane)" should have been a suitable outing for the band's love of a soulful groove, yet desperately lacked the original's urgency.

A final run around the back catalogue was eagerly welcomed by a crowd dominated by older fans, desperate to sing along to earlier successes. There was no "Alright", yet the Buzzcocks-meets-Who pizzazz of "Caught by the Fuzz" and the choppy Led Zep rifferama of "Lenny" reminded us of the group's glory days. The bath water may have become stagnant, but there was a real sense Supergrass had chucked out the baby.