John was a chorister at Westminster Cathedral before reading music at Oxford University, where he also played drums in jazz and pop bands and developed an interest in electronic music. He has written for choirs including Commotio, Westminster Cathedral Choir and East Oxford Community Choir, and has written commissions for the Edington Music Festival, Crossover Intergenerational Dance Group, Oxford Youth Dance and The Oxford-Grenoble Association. In 2006 John co-founded Oxford-based choir Sospiri with Chris Watson. Sospiri specialises in liturgical singing of plainsong and sings Latin Vespers at Merton College each term, as well as performing regular concerts. Since 2007 John has written a series of settings of World War I poetry, a number of which were recorded by Commotio and included in their disk; Night (released by Herald, 2007). A more recent set was recorded by Sospiri for a disk titled Requiem (The Gift of Music, 2010).