Tansy was born in Bristol in 1973. In 1996 she was a BBC Young Composer, and subsequently studied at the Guildhall School of Music and Drama and at Royal Holloway College.

She rose to further prominence on the British scene with a sequence of ensemble works for the Composers Ensemble (Patterning), the London Sinfonietta (Torsion) and The Brunel Ensemble (The Void in this Colour), all of which bear the hallmarks of her apprenticeship under Simon Bainbridge and Simon Holt.

In her recent work, Davies has found an accommodation between the worlds of the avant-garde and experimental rock, between, in the words of one critic, Xenakis and Prince. Filled with sounds of cracking, slapping, whipping and scraping, it is music that is utterly contemporary, inhabiting the same urban landscape as industrial techno and electronica, and while Davies is similarly fascinated by the potential of ‘looping’ as a structural device (as in her work ‘neon’), there is none of the formal predictability of much commercial dance music. Rather, the skewed proportions of works such as her London Symphony Orchestra commission Tilting attest to her keen interest in applying structural principles found in the natural world, or the work of architect Zaha Hadid.

Tansy has been commissioned by numerous world class ensembles and orchestras, including the London Sinfonietta, the Britten Sinfonia, the City of Birmingham Symphony Orchestra Youth Orchestra, the City of London Sinfonia, BIT 20, the Northern Sinfonia, a large-scale multi-media work Elephant and Castle for the 2007 Aldeburgh Festival, the BBC Concert Orchestra as part of their of their Discovering Music series on Radio 3, and a large scale piece for the BBC Symphony Orchestra, Wild Card, for the Proms in 2010.

Her work is performed internationally, by groups including the Cantus Ensemble, Grup Instrumental de Valencia, the Tiroler Ensemble für Neue Musik, Musiques Nouvelles, the Melos Ethos Ensemble, the Orchestra of Filharmonia Baltycka, the Israel Contemporary Players, the Winnipeg Symphony Orchestra, the Orquesta Sinfonica de Chile, the Tokyo Symphony Orchestra, and the Plovdiv Philharmonic at WMD/ISCM 2011 in Zagreb. In 2009 she received a Paul Hamlyn Award.

In 2010 the critically acclaimed As with Voices and with Tears, a requiem for choir, string orchestra and electronics, was performed to commemorate Remembrance Sunday in Portsmouth Cathedral, with the London Mozart Players. This work was nominated for the South Bank Show/Sky Arts Award 2011. Also in 2011, Tansy’s much-admired album Troubairitz was released on the Nonclassical label and she collaborated with Norwegian choreographer Ingun Bjørnsgaard on Omega and the Deer, a dance project which toured Oslo, Berlin, Potsdam, Hamburg and New York. Later that year her carol, Christmas Eve, was performed at the Festival of Nine Lessons and Carols in King’s College Cambridge and broadcast around the world.
2012 saw two new premieres; a new piano concerto for Huw Watkins and the Birmingham Contemporary Music Group and a wind nonet for the City of London Festival.