You write the reviews: Portico Quartet, SOAS Brunei Gallery, London

"We all live together, you see, and tonight this is for Jack," says Nick Mulvey, pointing at the saxophonist, who sports the looks of Jude Law and a chunky Norwegian jersey. "He sleepwalks and fell down the stairs last night." It's a genial way for the hang-player to introduce "Steps in the Wrong Direction", a track from this new band's first CD, Knee-Deep in the North Sea.

And the hang is why we have come along to see them. After hearing a track from their compelling disc on Radio 4's Front Row, I shot online to dig up details of the group's next gig; and judging by the tumultuous applause at the end of their short set, I am not the only one sensing that the Portico Quartet are a phenomenon in the making.

The hang is a domed steel percussion instrument, and several of these wok-like things, each tuned to a different key, were handed around the stage like totemic flying saucers. The instrument can sound like a doleful Cuban piano or a lyrical steel drum, surge forward in a hypnotic bass track or soar like a soulfully resonant gamelan. Two of the four young men in this group, who met while studying music at the University of London's School of Oriental and African Studies, took it in turns to stroke very individual responses out of this impressive piece of music-mongery.

It may sound mythic, but it's apparently true, that the hang's inventors will not agree to sell one of their creations before the would-be suitor has undergone a gruelling interview in Switzerland. Having, I guess, soared over that hurdle, the quartet have been busking in Europe as well as on London's South Bank, and clips on their Myspace page demonstrate how this has honed the band and their sound. But what gives this strange yet perfectly balanced meld its lyrical lead is the soprano saxophone: Jack Wyllie plays up a storm, belying his expression of slightly startled detachment.

The pellucid and seemingly effortless sound on "(Something's Going Down on) Zavodovski Island" turns stormily onomatopoeic during the album's title track, while the waltz-time "Pompidou" displays Gallic undertones, befitting of a track composed during their busking days in Paris.

The rather corporate surroundings of the Brunei Gallery theatre space fails to dampen the audience's gusto or disrupt the band's control. They are set to be jazz/world/classical's first barnstorming boy band, but don't let that put you off them or this unmissable musical departure.

Louise Hayman, lawyer, London

Touring to 17 May (www.myspace.com/porticoquartet)

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