Les Triaboliques, The Lexington

London-based trio Les Triaboliques should perhaps be grateful that Wikipedia hasn’t included them in their entry on supergroups. There you will find a comprehensive list of so-called supergroups with leadenly histrionic names like Isles and Glaciers, Shrinebuilder and How to Destroy Angels (not to mention the super-supergroups that started it all such as Cream, Humble Pie and Crosby, Stills, Nash and Young. But Adams, Edmonds and Mandelson are, I suppose, the alt-supergroup, representing something of an evolutionary jump forward - if for no other reason than they are musically co-operating rather than competing, admirably intent on suppressing their egos rather than indulging them.

These three distinguished gentleman who sat before us last night in the dimly lit, flock-wallpapered upstairs room of a pub in King's Cross have, between them, played with the likes of Robert Plant, Jah Wobble, Sinead O’Connor, Magazine, PIL, Billy Bragg, The Mekons and The Waterboys, as well as fronting and producing dozens of their own projects. So do they display any of the leanings towards self-importance and grandiosity we so love to hate in supergroups?

Well, the cover of their debut CD rivermudtwilight does boast the same opaquely romantic blurb, fit to grace any 1970s gatefold LP sleeve: “Crossing the stone bridge between dark city and dusk. On the creaking causeway, instruments on backs, rain on our packs. We smell the black earth. We are intent.” However, intentions are all very well, but once they’d shrugged off their sopping, mud-encrusted gear, did they deliver?

The answer is: absolutely, in that they charmed the crowd with lots of oblique musicians' banter while somehow finding time to fit in some rousing, often delightfully uncategorisable music. It has to be said that as a fan of popular beat music – the kind of stuff that gets your limbs moving and your pulse racing – I was somewhat taken aback to see that our three musicateers were, to a man, firmly planted on seats, with the one person in the band who you’d expect to see on a seat – the drummer – conspicuous by his absence.

But then it gradually dawned on me that this was the whole point of Les Triaboliques: to put the focus on all the glorious tones, textures and timbres of stringed instruments both acoustic and electric - from the mandolin to the cümbüş (it's pronounced jümbüsh) - without the bombast of a drum kit supposedly to legitimise what they were doing. They wasted no time by opening with the low-slung, subtly emphatic “Crossing the Bridge”, somewhat extending in length from the album version so the band could relax into an intricate and compelling dialogue between their instruments, with the friendly growl of Adams's Gibson guitar keeping everything earthbound and primal.

And the whole chair issue was quickly dispelled. One minute the three of them would be sliding around – like kids desperate for the school bell to ring, feet insistently tapping, a leg occasionally kicking the air, as if they too were wondering why they weren’t standing up - and the next, they might as well have been in rocking chairs on some far-away porch; just three old blokes (sorry, middle-aged blokes) in Mississippi, or New Orleans, or Paris, relaxing into the Bill Frisell-ish groove, for there own pleasure as much as for ours.

Even the one track I invariably skipped on the album – a cover of “Don’t Let Me Be Misunderstood” – momentarily made me forget that sublime Nina Simone version, thanks to Lu Edmonds’s intense and focused vocal which was somewhat reminiscent of the archly theatrical overhaul Alex Harvey gave “Delilah” back in 1975. But as with the album, the high points were when the band played more groove-orientated material, such as the Beefheartian “Black Earth Boys”.

As they locked into each other’s playing, Adams would take one of his coruscating pseudo-primitive solos, making you concerned about whether he would get through it, fingers unshredded. In the meantime, Edmonds and Mandelson might be seeing how far and how quickly they could travel up the fretboard of their respective esoteric instruments, getting them to scream like cats on heat in the process. And all this for the love of organised noise. But the bottom line is, I didn’t miss the prosaic four-to-the-floor racket of a kit drum; the supposed essential ingredient of a rock/blues band. So, mission accomplished, gentlemen.

• Book tickets for Les Triaboliques on tour until 13 May then at the Salisbury Festival on 21 May

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Les Triaboliques perform "Black Earth Boys"