Tallis’s monumental Spem in alium is one of the greatest glories of Western polyphony, and its pre-echoes and aftershocks reverberate through all the other pieces on this disc. The National Youth Choir of Great Britain’s massed voices shed dazzling light on its programme of polychoral works from the fifteenth and sixteenth centuries, interspersed with virtuoso tributes from three leading contemporary composers including Gabriel Jackson’s own towering 40-part motet Sanctum est verum lumen.