Mary Ringsleben was an original signatory of the Committee of 100, which was founded on the initiative of Ralph Schoenman and Bertrand Russell in October 1960. This Committee called for a mass movement of civil disobedience against British government policy on nuclear weapons. Its members saw a need for more radical methods than those used by the Campaign for Nuclear Disarmament, especially following the defeat of the Labour Party in the 1959 general election

Based in Leeds, she was an organiser of the Northern Direct Action Committee.

Ringsleben was awarded the degree of Ph.D. from Aberdeen University in 1956 for her work on Gavin Douglas - a Scottish bishop, makar and translator. She had been in contact with Scottish writer and poet Hugh MacDiarmid (Christopher Grieve) about it, and he had lauded her work.