There are major premieres to come at the Proms next week from big hitters such as Andriessen and Glanert, but if either of those comes anywhere near Unsuk Chin's new Cello Concerto for originality, aural beauty and expressive depth, we shall be very lucky indeed. Chin won the prestigious Grawemeyer award in 2004 for her previous concerto, for violin, but the new work, a BBC commission, is more considerable in every respect. Where the violin work grafts beautifully imagined instrumental textures and tricksy solo writing on to a disappointingly conventional musical framework, the cello concerto is strikingly fresh. Its four-movement outline may also seem quite conventional, but the shape and trajectory of those movements are anything but.
Everything grows from the theme assembled around a single pitch in the opening bars, and the first movement alternates discursive ruminations for the cello with chiselled commentary from the orchestra, until everything boils up into a fierce cadenza. If the scurrying second movement is over almost before you've noticed it, the third is an elegy for the cello, clothed in ravishing harmonies from the orchestra, which more than anything else in the work recall Chin's teacher, Ligeti. The finale defies expectation again with a sequence of attempts to launch a major dialogue between cello and orchestra for which neither has the appetite, and which resigns itself instead to an enigmatic return to the mood of the opening.
The hugely challenging cello part was composed specifically for Alban Gerhardt, who made its difficulties and teeming luminous detail seem the most naturally expressive things in the world, playing from memory and maintaining perfect coordination and balance with Ilan Volkov and the BBC Scottish Symphony. It's a major addition to the concerto repertory.
The Proms continue until 12 September. Details: bbc.co.uk/proms