Marion Ross was the eldest daughter in a family of 5 girls. Her father, William Baird Ross was a well-known organist and composer of organ music. For one year she worked as a crystallographer in Manchester University collaborating with Dr C A Beevers. They investigated the crystal structure of a molecule, 'beta-alumina' and published their results in a German journal in 1937. They found a problem anomaly in the structure where sodium ions were present, and these locations came to be known as Beevers-Ross, or anti-Beevers-Ross sites. They could not at the time see any practical application for these, and simply noted them as interesting. Years later, it was discovered that the mobile sodium ions form excellent fast ion conductors, very useful in battery technology.
Marion Ross went on to work in the fields of nuclear and X-ray physics, hydrodynamics and acoustics, supervising many students. She took a keen interest in the construction of the Royal Festival Hall in London, one of the first concert halls to be designed for its acoustical qualities, not entirely successfully.