Traditionally, Judas is the agent of darkness in the Passion story. But what if, as revisionists might argue, he was the agent of God – or at least, of the inevitable: a pawn in the game, more fall guy than bad guy? That’s the argument of The Judas Passion, a new work by composer Sally Beamish that played at John’s Smith Square, taking its lead from the Passions of JS Bach but with more questioning, less orthodoxy. Written to a text by David Harsent, a poet known for the portentous spareness of his opera libretti for Harrison Birtwistle, it spoke largely in the familiar language of Scripture but homed in on the idea of Jesus and Judas as counterparts: two men obeying destiny, enacting what was chosen for them. Judas summed things up in a repeating statement, “I do it because I must”; and as a piece of storytelling it was radiantly clear. But it was also slow of pace, without the drama of the Bach Passions and not helped by a semi-staged presentation that came stiff with self-conscious reverence. Bach and Scripture were in fact the problems with this Passion: it was too in awe of its own precedents to have a sense of self. And that the scoring was for period instruments – here the Orchestra of the Age of Enlightenment under Nicholas McGegan – camouflaged its newness. Beamish, a composer I’ve admired of old for her distinctive voice, doesn’t surrender to baroque pastiche: the idiom is nervously contemporary. But nervous is the word. This should have been a bold, assertive work given the good idea behind it, but the actuality was thin and plodding, without strong enough material to hold an audience or give the singers – Roderick Williams, Mary Bevan and Brenden Gunnell in the lead roles – something worth their talent. All this year there has been a broad theme – Cello Unwrapped – running at Kings Place; and the other week it unwrapped the cellist Natalie Clein, pianist Julius Drake and mezzo Fleur Barron in a programme of instrumental and vocal music so eclectic it shouldn’t have worked, but somehow did. Sweeping without rhyme or reason through Bach, Berkeley, Janáček, John Tavener and John Cage, the only thing that held it all together was a blinding sense of purpose from the artists, whose musicianship was so impressive you took everything on trust. Fleur Barron’s super-cool poise was fascinatingly at odds with Clein’s intense self-agonising (as though every note occasioned her extreme pain). But by different means they found a shared truth in the music they delivered. Voice and cello aren’t a common pairing but they fit; and better than you’d think.