Ok, Mike, I am perfectly happy to extend this to other 20th century choral works

So.....among my own personal favourites would be:
Bernstein Chichester Psalms
Bloch Sacred Service
Britten Cantata 'St.Nicholas'
Durufle Requiem
Dyson The Canterbury Pilgrims
Elgar The Spirit of England
Finzi Intimations of Immortality, 'In terra pax'
Hindemith-Requiem 'When Lilacs Last in the Dooryard Bloom'd'
Holmboe Requiem for Nietzsche
Holst Choral Symphony, Hymn of Jesus, Ode to Death
Honegger-, 'Le Roi David", Christmas Cantata
Herbert Howells-Hymnus Paradisi, Stabat Mater, Missa Sabriensis
Janacek Glagolitic Mass
Ludvig Irgens Jensen 'Heimfred'
Kodaly Psalmus Hungaricus, Budaveri Te Deum
Jon Leifs-Iceland Cantata
George Lloyd Symphonic Mass, Litany, 'The Vigil of Venus'
Frank Martin-Cantata 'Pilate', Requiem
William Mathias-'Lux Aeterna'
Novak-'The Storm'
Orff-Carmina Burana
Penderecki-Polish Requiem
Poulenc-Gloria
Rachmaninov-The Bells
Rubbra-Advent Cantata 'Natum Maria Virgine'
Schoenberg Gurreleider
Suk-Epilogue
Szymanowski-Stabat Mater
Vaughan Williams-Cantatas 'Dona nobis pacem', 'Hodie', 'Toward the Unknown Region'
but others deserving a mention would include John Adams 'On the Transmigration of Souls', the various Cantatas written for special occasions by Hugo Alfven(like the Cantata for the 400th Anniversary of Uppsala Cathedral or the Cantata for the 1917 Reformation Festivities in Uppsala), Britten's Cantata Academica, Foulds' World Requiem, Constant Lambert's 'Summer's Last Will and Testament',
Markevitch 'Lorenzo il Magnifico', Martinu's Czech Rhapsody, the Menotti Cantatas, Knut Nystedt's 'Apocalypsis Joannis', Pfitzner's Cantata 'Von Detscher Seele', the Prokofiev Cantatas("On Guard for Peace", Cantata for the 20th Anniversary of the October Revolution),
Schnittke's Cantata 'Nagasaki' and Faust-Cantata, the short Sibelius Cantatas, Richard Wetz's Requiem.
Oh...I have probably forgotten many others!
Anyway, happy to discuss any of these
