Her career started in Baroque music performing with leading established groups such as The Consort of Musicke, Chiaroscuro and Drottningholm Barockensemble at the Proms and for Belgian, Israeli and Danish Radio. She has recorded songs by Purcell and Händel for Nuova Era. Since 1990 she has been a regular soloist for BBC Radio 2 and as a recitalist she performs regularly at St John's Smith Square and she has sung for Classic FM and Danish Radio. Concert engagements in recent years have included Beethoven's Ninth Symphony in Bath and Missa Solemnis in Gloucester Cathedral, Mahler's Second Symphony, Brahms’ Requiem at Birmingham Symphony Hall and his Liebeslieder Waltzes and Rossini’s Petite Messe Solennelle for St Albans Choral Society, Haydn’s The Creation at St Alban's Abbey and a Schubertiade for the 2006 Hampstead and Highgate Festival. In 2007 she sang Haydn’s Nelson Mass conducted by Ron Corp for the festival, in a summer gala concert with Bushey Symphony Orchestra and in Haydn’s The Creation with the Bridgewater Sinfonia (then the Bridgewater Band) and the Chiltern Chamber Choir.

Marianne started her operatic career in 1996 and she has premiered many contemporary roles here and abroad. Other roles include: Adina/ L’Elisir d’Amore, Mimi/La Bohème, and Belinda/ Dido and Aeneas. Since 1999 she has understudied for Glyndebourne where roles include: Servilia/ La Clemenza di Tito, Diane/ Iphigénie en Aulide, Bertha/ Euryanthe and the title role in Rodelinda. This production travelled to Châtelet, Paris in 2002. In 2004 she joined the Royal Opera House Chorus and also understudied the Female Convict in the ROH's Lady Macbeth of Mtsensk. In January 2005 she had her Royal Opera House, Covent Garden debut in Turandot, and later that year also she has understudied the role of Gerhilde in the ROH’s production of Die Walküre, which also was performed at the BBC Promenade Concerts. In 2006 she understudied the roles of Esmeralda in the ROH’s production of The Bartered Bride and Chloë in The Queen of Spades.