Those of us who relish the barbed provocations of earlier Kagel – Acoustica, Ludwig van and Staatstheater, late ’60s/early ’70s pieces that posed uncomfortably refreshing questions about classical tradition – are apt to feel slightly disappointed when faced with the more accommodating surface of a work such his String Quartet No 4 from 1993, when Kagel had cultivated a respectable, clubbable veneer. The surface of his quartet explicitly evokes the Bartók of the Fourth Quartet. Folksy melodies and inchoate dance forms assert themselves forcefully. But, sooner or later, the realisation dawns that all is not quite what it seems. When trying to encrypt a Kagel score, the surface is the last place you should look.

Kagel contours melodies that might be folk tunes but it’s impossible to tell because he disrupts the harmonic underpinning so fundamentally. Chord sequences eat themselves; meticulously prepared cadences fall over; Kagel sets up expectations but then sprints the other way. And the music remains in uneasy, unsettling flux, occasionally spilling over into pockets of raw timbral anarchy. Kagel asks: what are your associations with folk material, and why listen to it played by a string quartet anyway? That well-behaved exterior was, for sure, a veneer.

The Lagos Ensemble, with guest viola player Kyra Philippi, shepherd Kagel’s dispersing fragments into a robust, malleable continuum. So physically powerful is their performance that, sadly, Keuris’s First Quartet gets crushed in its wake. Extreme textures every place: but Kagel demonstrates that it’s how forcefully sound can corrupt the structural narrative that counts.