During the first minutes of Alston's latest work, it takes a serious effort of will to focus on the dance. At the back of the stage are 19 boys from Canterbury Cathedral choir, who sing the music for his setting of A Ceremony of Carols. Mere children, they hold the theatre captive – not only with the purity of their voices, but with their heart-wrenchingly adult ability to hold Benjamin Britten's complex harmonies in tension.

But if the music sometimes seems to be a world within itself, Alston knows what he's doing. Having expanded his company to 16 dancers here, he finds within the score a deep choreographic structure. Ceremony is less about the large, swinging, angled shapes of its steps than about the formal relation of dance to music. In great folding waves of repeating movement and in lines of close contrapuntal opposition, Alston captures the soaring ecstasies and dark mysteries of Britten's musical vision.

Ceremony is a fine offering to the newly rebuilt Marlowe theatre, which co-commissioned it. But it would be even better with a visual redesign. While the deep red of the dancer's tunics is striking against the choristers' purple robes, starker, stranger costumes would highlight the otherworldly quality of the music – as would less blandly uniform lighting.

Alston's own work makes up the entirety of this Canterbury programme. Along with a blithely excellent revival of 2011's Roughcut is his recent Unfinished Business, set to Mozart piano music. Here, the interaction with the score lies more in the detail: the arc of a musical phrase that breathes through a string of turning jumps; the clustering of dancers round a dense melodic variation; the briefly intense relationship that forms between the quiet clarity of one solo dancer and the antic energy of his male partner. It's a moment of musical storytelling, transient but beautifully judged.