Mary Newcomb was born in Harrow-on-the-Hill in 1922. In 1943 she was awarded a B.S.c in Natural Sciences from Reading University, and a Diploma of Education the following year. Between 1944 and 1950 she taught science and mathematics at the high school in Bath.
Newcomb’s first one-man show was held at Crane Kalman Gallery in 1970. The gallery has continued to mount regular exhibitions of her work since then. In 1996, the author Christopher Andreae produced a monograph of the artist in association with Crane Kalman Gallery. Newcomb was greatly overlooked by the established art world, painting for around forty years before she was acknowledged by the establishment when the Tate Galley, London purchased a large work entitled 'People walking amongst small Sandhills' in 1997.
In 1950, Newcomb married and moved to Norfolk. She also spent considerable periods of time living in Suffolk. Newcomb’s rural surroundings are the subject of most of her works, although she does not paint in a naturalistic manner. The simplicity of Newcomb’s style gives her art an immediacy, which should not be confused with naivety. The explanatory way in which Newcomb titles her paintings, for example, 'These sheep find it necessary to cross the bridge', further illustrates that her aim is to capture moments and memories rather than to ‘create art’.