Painter, draughtsman and printmaker, she was born in London. Studied at Slade School of Fine Art with Norman Janes and Randolph Schwabe. Exhibited WIAC, Redfern Gallery, with Newbury Art Society and abroad. For much of her life Casbolt suffered poor health, but this did not prevent her producing fine landscapes and abstracts in the late 1950s and early 1960s. Lived in Newbury, Berkshire, later in southwest London.