Seán was introduced to music through the Irish fiddle tradition of his hometown of Derry. He read music at St John’s College, Cambridge, after which he completed a PhD at Trinity College, University of Dublin. He is now a lecturer in music in Dublin City University. He is active as a choral singer, singing with the internationally acclaimed New Dublin Voices, conducted by Bernie Sherlock.
Seán’s choral works have garnered numerous awards: he has won the Feis Ceoil choral composition award four times (2009, 2011, 2014, 2016), the Choir and Organ Magazine composition competition twice (2012, 2014), the St Giles's Cathedral Edinburgh anthem composition competition, the Fragments Choral Composition Award (in association with Historic Scotland), and the Prix pour une œuvre de création at the international choral festival Florilège Vocal de Tours, France. His choral works have been performed by choirs including the choir of Merton College, Oxford, the choir of Salisbury Cathedral, the National Youth Choir of Scotland, the choir of St Giles’ Cathedral, Edinburgh, Chicago a cappella, the Grant Park Chorus, Chicago, Laetare Vocal Ensemble, Voci nuove, the Mornington Singers, and New Dublin Voices.
Seán has also written much chamber music: he has twice been awarded the Young Composers’ Bursary at the West Cork Chamber Music Festival (2013, 2014), the Jerome Hynes composition competition (2011), was a finalist in the BBC Radio 3 / National Centre for Early Music’s Composers’ Award 2013. He was commissioned by the Vanbrugh Quartet to compose his String Quartet No. 3, 'The Devil's Dream’ for their Crossings Project, by the West Cork Chamber Music Festival to compose Lament for the Poets 1916 for the Vanbrugh Quartet and soprano Caroline Melzer, and by the Estovest Festival to compose No Go for Xenia Ensemble and uilleann piper Eoin O’Riabhaigh.
In 2012 he was commissioned by the Legacy Trust UK to compose a chamber opera, Number Seven, for the Cultural Olympiad, part of the 2012 London Olympics, in collaboration with author Carlo Gébler. In 2015, he was selected for the 'Adopt a Composer' programme—in association with Making Music, PRS for Music, Sound and Music, and BBC Radio 3—for which he composed Hive Mind, premiered at the Barbican Centre, London by the Kensington Symphony Orchestra.
Seán is a member of the Irish Composers’ Collective, the Association of Irish Composers, and is represented by the Contemporary Music Centre, Ireland.