She has composed over 80 published works and her music has been performed in many countries. She has written chamber, vocal, choral, and orchestral music spanning from Elegy-Symphony (St Louis Symphony Orchestra, 1981) to TIrluniau/Landscapes (BBC commission, BBCNOW, Proms 2000); in 1983 she won the ASCAP/Rudolf Nissim Prize for La Belle Dame sans Merci. She has also written about music; as co-editor of the New Grove (Norton) Dictionary of Women Composers, she has been at the forefront of issues concerning gender and music. She also writes on the operas of Harrison Birtwistle, having been commissioned by the Royal Opera House, Covent Garden, to write programme essays on both Gawain and The Minotaur. Her most recent CD, Light and Water, is issued on the Deux-Elles label. In 2006 she was awarded the Glyndŵr Award for an Outstanding Contribution to the Arts in Wales.
Her work Path Through the Woods for recorder and strings was premiered in April 2011 by Pamela Thorby and the Welsh Sinfonia, conducted by Mark Eager.