It's often the familiar, hackneyed pieces which most fully reveal the character of an ensemble or performer, the mirror in which their interpretive mettle is most fully reflected. In that respect I've no hesitation in saying this is the finest performance of Barber's Agnus Dei I've heard by any choir, live or on record. The sustained tonal plenitude and fabulous breath apportioning of the sopranos in the opening paragraph; the organic emergence of other voice-parts as the textures alter, and the slow-burn kindling of an eventually incandescent climax—these mark the performance with a special intensity gripping the attention in every bar of music.

There's more Barber: the jabbing accents of 'Mary Hynes' from Reincarnations are deftly differentiated, summoning the joyful buoyancy the composer was aiming for, and the suddenly benumbed decrescendo Polyphony singers achieve on the last word ('grief') of ‘Anthony O'Daly’ is further evidence of how totally their consummate technique is placed at the service of a piece's meaning and intention. In the third setting, 'The coolin', the enveloping sensuality of the Irish bardic poetry is beautifully rendered in the supple phrasing of the choir, and the affectionate caress of Stephen Layton's conducting.

In Bernstein's Missa brevis, the singers' electrifying attack, the sentient countertenor solos of David Allsopp, and the peal of tubular bells make for another riveting account—the three combine to particularly ravishing effect in the Benedictus. The clashing harmonies between upper and lower voices at the start of the Agnus Dei are held in perfect counterbalance, the moment tense but not melodramatically overstated.

Topping and tailing the programme are two works by Randall Thomspon. Tenderness is the keynote of both performances; Alleluia the composer's anxious, muted response to the Nazi occupation of Paris in 1940, Fare Well his pained response to the intimations of mortality in Walter de la Mare's poem.

A strongly purposeful account of Copland's Four Motets belies the composer's own modest assessment of the work, while among the other pieces Barber's raptly expectant 'A nun takes the veil 'Heaven-haven' again confirms the stellar levels of choral technique and interpretive insight achieved by Stephen Layton and his singers.

Hyperion's engineering achieves a virtually ideal balance between allowing a degree of resonance from the church acoustic to warm the textures, and shining light into the inner workings of the vocal writing. That clarity increases exponentially if you buy the recording in the higher-resolution format available on the Hyperion website. A wonderful recital, not to be missed.