In 2000, Fox made her debut for the Glyndebourne Festival as Karolka, returning in 2002 as Zerlina and in 2003 as Susanna. Of her Susanna in Le Nozze di Figaro at the Glyndebourne Festival Barbarina Diana, writing in Il giornale della musica described her performance at Glyndebourne as "a delight for the eye and heart, whose voice, fresh and crystal clear is blessed with a rare beauty accompanied by a strong musicality: 'Deh vieni' interpreted without affectation, directed to her beloved, takes your breath away". With Glyndebourne on tour she has sung Marzelline and Miss Wordsworth. In 2004, she made her debut with the Royal Opera Covent Garden as Woglinde, returning to the house in 2005 as Waldvogel and in 2006 as Woglinde. In 2007 she sang Zerlina and Woglinde with English National Opera, Merab, Musetta and Mimi with Opera North, and Servilia with Welsh National Opera. At the Edinburgh Festival, her roles have included Iphis and Cleofide. Fox made her international debut as Ilia with De Vlaamse Opera. In 2005, she made her debut with the Bayerische Staatsoper in Munich as Michal, returning to the house in 2006 as Eurydice. In 2008 and 2009, she sang Asteria in Handel's Tamerlano. She is scheduled to revive the role opposite Plácido Domingo at the Gran Teatre del Liceu in Barcelona in 2011. She made her debut at the Salzburg Festival in 2005 as Second Niece and returned to the Festival in 2007 as Woglinde. Further European engagements include Susanna for the Royal Danish Opera, Arianna for the Nationale Reisoper and Karolka at the Deutsche Oper Berlin. In 2004, Fox made her North American debut as Zerlina at the Cincinnati Opera. Fox has an extensive concert repertoire and has been particularly associated with the British Broadcasting Corporation, The Bach Choir and the Choir of King's College, Cambridge. She has also performed abroad with many of the world's leading orchestras including the San Francisco Symphony, the Chamber Orchestra of Europe, the Berlin Philharmonic and the Minnesota Orchestra. In 2009 she performed with the City of Birmingham Symphony Orchestra in Mahler's Symphony No. 2; toured throughout Europe and the USA in Handel's Athalia with Ivor Bolton and the Concerto Koln; and sang in Handel's Acis and Galatea with the Gabrieli Consort at the Beaune Festival. She also starred in the BBC MGM Prom with Sir Thomas Allen, Seth Macfarlane, John Wilson and the John Wilson Orchestra in 2009. She appeared once again at The Proms in 2011, with the John Wilson orchestra and stars of musical theatre.
