novelist Keri Hulme on an opera Ahua (2000), the story of the Ngāi Tahu ancestor Moki. It was commissioned by the Christchurch City Choir. In 2004 he collaborated with Jeremy Commons on The God Boy an opera based on the novel by Ian Cross. It was performed by Opera Otago for the Otago Festival of the Arts. Ritchie set works by Dunedin poet Elena Poletti to create Lullabies (2015) which were originally commissioned and performed by the Auckland Choral society. Ritchie, while not a gamelan player, was attracted to the sounds of gamelan and used gamelan scales in his symphony Boum (1993) and in his piano piece 24 Preludes (2002). 24 Preludes display many different musical influences: neo-Romantic composers, a range of time signatures, contrapuntal and harmonic styles, harpsichord and organ techniques, gamelan and celesta. Ritchie was also trying out the use of the mathematical concept of the magic square also used by composers Peter Maxwell Davies and Gillian Whitehead. The preludes were written when Ritchie took some time off from his freelance work to explore different approaches to composition. Ritchie's oratorio Gallipoli to the Somme which commemorated the one hundred year anniversary of the Battle of the Somme was based on the book of the same name by Alexander Aitken, who was a soldier in the Otago battalion and later professor of mathematics at Edinburgh University. The oratorio had its premiere in Dunedin in 2016. Its European premiere, with Anna Leese as a soloist, was at the Sheldonian Theatre, Oxford in June 2018. It was voted New Zealand's most popular piece of classical music in RNZ Concert's Settling the Score poll in 2020. In 2018, after 18 years of teaching composition, Ritchie became professor of composition in the Department of Music, Theatre and Performing Arts at the University of Otago. In 2020 he became head of the School of Performing Arts, a three-year position. Award and honours Ritchie received a Trust Fund award from the Composers Association of New Zealand in 1998 in recognition of his achievements in composition. Selected works Concertino for Piano and Strings, op. 8 (1982) Piano Concerto, op. 9 (1982) Flute Concerto, op. 56 (1993) Symphony No. 1, Boum, op. 59 (1993) Viola Concerto, op. 64 (1994–95) Star Fire, opera, op. 68 (1995) Cartoon: Fantasy for Soprano Saxophone and Orchestra, op. 70 (1996; revised in 2002 for release as "Oboe Sonata", op. 70b) Guitar Concerto,