James studied composition with Robin Holloway at Cambridge University, where he was a Music Scholar and Choral Exhibitioner at Girton College. He has had music performed by English Voices, the choir of St Paul’s Cathedral, London, the choirs of Trinity College, Cambridge and Vivamus, with recordings by the choirs of Girton and Selwyn colleges. Recent commissions include music for the Songmakers’ Almanac A Night in Venice at the Wigmore Hall, music for internationally renowned organist Guy Bovet, two organ voluntaries for a special service in King’s College Cambridge celebrating the university’s 800th anniversary, and an anthem for James Bowman with the Chiesa Consort, the last of which won the 2006 Choir and Organ magazine carol competition.

He has written scores for numerous theatrical productions, including musicals Miracles at Short Notice (MusicalTalk's pick of the 2011 Edinburgh Fringe), award-winning 2007 total Fringe sell-out show Tony Blair – the Musical (“runs the melodic gamut from near-Weillian severity to knowingly schmaltzy balladry, and is packed with rich, tight harmonies” – The Daily Telegraph) and his 2006 one-man show The Rise and Fall of Deon Vonniget (“very funny…fantastically skewed” – the New York Times). Other productions, as both a composer and musical director, include The Borrowers (Dreamshed Theatre, 2010), With Blacks (collaboration with Jack Thorne for the Alight Here Festival, 2003), Lysistrata (Watford Palace Theatre, 2009), The Snow Spider (Tristan Bates Theatre, 2011) as well as a setting of new words by Andrew Motion for Bush Theatre’s Sixty-Six Books at Westminster Abbey, Lost! (Kensington Temple, 2005), Richard Taylor’s Whistle Down the Wind (Cambridge, 2005), NewsRevue (London, 2008), Lysistrata (Watford, 2009) and The Snow Spider (The Roundhouse, 2010). He has also scored several short films, including The Ghost of Kirkton Fell (Hired Thugs Productions, 2004), Summer's End (Hired Thugs Productions, 2005), Hide and Seek (Talk to Rex Productions, 2006) and Savage Mountain (Steve Warne, 2010). For several years he has taught composition, 20th Century Music and other subjects in the Cambridge University Music Faculty.

Between 2008 and 2011 James was composer-in-residence at Bedford school and from April 2012 he will be taking on the role of Director of Music at Westminster Abbey Choir School.