A true contralto with a wide vocal range, she has excited the attention of many contemporary composers. In 1999 she created the role of Stella in Elliot Carter’s opera What Next? for the Staatsoper unter den Linden conducted by Daniel Barenboim; she has subsequently performed this work under Peter Eötvös, Oliver Knussen and Kent Nagano. She created the role of Irma in Eötvös’s opera Le Balcon at the 2002 Aix en Provence Festival and toured with the production in Europe. Since 2002 she has performed Boulez's Le marteau sans maître throughout Europe with the Ensemble Intercontemporain under the direction of Boulez himself as well as with several other ensembles and conductors, most recently at the 2012 BBC Proms under Franz-Xavier Roth; she recorded the work with Boulez on Deutsche Grammophon to much critical acclaim and a Grammy Award. As part of the celebrations of the composer’s 80th birthday she performed Le visage nuptial under his direction with the Chicago Symphony Orchestra in Chicago.
In Britain she has forged a special relationship with the composer Michael Nyman, recording several of his film scores and touring the world with the Michael Nyman Band. She also works frequently with the composer Joby Talbot and sings on his soundtrack to the film The Hitchhiker’s Guide to the Galaxy and television series The League of Gentlemen. Hilary has also made a considerable name for herself as a fine interpreter of the Baroque repertoire, and sings regularly with many of Europe’s leading early instrument orchestras. These have included Christopher Hogwood and the Academy of Ancient Music, Paul McCreesh and the Gabrieli Consort, Christophe Rousset and Les Talens Lyriques, and The English Concert directed by Andrew Manze.
Operatically, Hilary is destined to play statuesque Handelian heroes such as Giulio Cesare or the god Mars (Legrenzi’s Il divisione del mondo) but occasionally has fun with such roles as the dominatrix Mescalina (Ligeti’s Le grande macabre), the Amazon Hippolyta (Britten’s A Midsummer Night’s Dream) or the bearded Baba the Turk (Stravinsky’s The Rake’s Progress). Other roles include the earth mother Gaea in Strauss’ Daphne and Mrs Sedley in Britten’s Peter Grimes (for Glyndebourne Festival Opera). She has played the role of the Washerwoman in Rob Zuidham’s Rages d’amour at the Nederlandse Opera in Amsterdam and sang Hippolyta for the Teatro Real, Madrid. In 2006 she sang in the first performances of George Benjamin’s opera Into the Little Hill in Paris and has since performed it in New York and throughout Europe. She created the role of Miss Prism in Gerald Barry's The Importance of Being Earnest, in concert performances and at the ROH Linbury Studio in 2013.