Whilst studying English at Oxford, she made her radio debut singing topical songs at the piano which were featured on Pick of the Week. This led to further appearances as a singer-songwriter with her trio Premier Cru and later as one-half of Casson and the Brannick Academy. Together they have written two CD's including Tutankhamun all Wrapped Up which were distributed to 65 thousand visitors to the 02 Tutankhamun exhibition.
Casson's first musical Two Tiger's based on the life and works of pioneering modernist writer Katherine Mansfield was the first by a woman to be shortlisted for the Vivian Ellis Prize. Shows since then include a series of collaborations with Tom Blackmore notably The Happy Prince based on Oscar Wild's short story, Requiem, a political review, and Persephone both with words by poet Simon Rae and most recently Dreams of Peace and Freedom, Song cycle for female voices and male narrator that explores the birth of modern human rights in Europe after the Second World War.