Inscribed to the memory of Grace Williams's friend Nancy Elizabeth Jenkins, who died of cancer shortly before the work was completed, Grace Williams's Missa Cambrensis is a full-scale setting of the Mass in Latin and Welsh, scored for soprano, alto, tenor and bass soloists, mixed chorus, boys' choir, orchestra and speaker. The orchestral forces required consist of two flutes (second doubling piccolo), two oboes, (second doubling cor anglais), two clarinets, bass clarinet, two bassoons, contrabassoon, four horns, two trumpets, two tenor trombones, bass trombone, tuba, timpani, percussion (two players: cymbals, glockenspiel, tubular bells, tamtam), piano and strings.