Fraser Trainer studied composition at Huddersfield University and the Guildhall School of Music and Drama as a postgraduate student, where he won the 1992 Lutoslawski Prize.

In addition to his five London Sinfonietta commissions, other ensembles to have performed his music include the Royal Philharmonic Orchestra, the BBC Symphony Orchestra, the Hallé Orchestra, the Gürzenich Orchestra, the Malaysian Philharmonic Orchestra, City of London Sinfonia, London Mozart Players, The Scottish Ensemble, Viva, Psappha, Kokoro and London Brass.

He has also been commissioned by violinist Viktoria Mullova, for Knots for solo violin and five players (2003) and the concerto for the living, for the 2005 BBC Proms (with the BBC Symphony Orchestra conducted by Martyn Brabbins). It was for this piece that Fraser received the runners-up prize for the BBC Radio 3 Award as part of the 2006 British Composer Awards.

Gadget, a concerto for Between The Notes and the Gürzenich Orchestra was given its premiere under the direction of Markus Stenz in a concert to celebrate the 20th anniversary of the Köln Philharmonie in 2006, and the London Mozart Players recently performed The Eye, a commission from the Cambridge Music Festival. In 2009 they went on to give the premiere of RESOUND, written to celebrate the 60th anniversary of the orchestra. RESOUND features fragments of Mozart's unfinished chamber music as well as excerpts of an archive recording of the LMP made in its earliest years of existence.

Fraser is currently working on a commission for an improvised concerto for Between The Notes and the Junior Guildhall Orchestra for performance in 2010.