In 1991, when Sir Harrison Birtwistle wrote a brief string quartet movement for the 90th birthday of his publisher, Universal Edition’s Alfred Schlee, it’s safe to guess that he did not expect to be adding another eight movements in similarly abrasive, fractured style over the next five years, and still less to be interspersing those movements with the nine settings of Paul Celan that complete the 18-movement Pulse Shadows.

When Pulse Shadows was recorded complete, the Arditti Quartet contributed the nine quartet movements. Hearing them independently, in this brilliantly intense and technically first-rate new version, reinforces the uncompromising blend of concentration and disruptiveness that the original movement – now titled ‘Frieze 1’ – sets out in embryo. With Birtwistle, musical motifs are not only mechanisms but also encapsulations of very human characteristics: so even when melody, as conventionally understood, is absent, the music can convey a sense of dramatic action and evolution that is far from soulless or, in the narrow sense, mechanical.

The longest of the Nine Movements lasts just over four minutes. The Tree of Strings (2007) runs for an unbroken 29 minutes and its ‘dramatic action and evolution’ is even more potent as a result. Evoking the Scottish island of Raasay, where Birtwistle once lived, and Sorley MacLean’s poetry, the music acts out – literally, on stage – the eventual depopulation of the space, as the players move apart and exit one by one, leaving an angry-sounding cello with a terse, repeated cadence-figure as the last word. Obviously enough, this theatrical aspect cannot be reproduced on audio disc, but The Tree of Strings still comes across as one of Birtwistle’s most powerfully sustained and expressively compelling musical designs.