Although born in Birmingham, Marian Darke came from a Welsh Communist family, her father being the long-term Welsh District Secretary, Bert Pearce (see separate entry). In her time, she held a variety of positions in the Communist Party and YCL from the 1960s onwards, from Secretary of a Party branch to being the last chair of the CPGB, dissolved in 1992.
After taking a degree in French and Russian at Birmingham University, she became a teacher and was active in the National Union of Teachers throughout the 1970s and attended her first national annual conference of her union in 1981. She was also variously a Divisional Secretary of the NUT and President of the NUT, during the 1990s. At this time she was a teacher of French in Kingston on Thames.
In internal Party matters, she supported the revisionist trend throughout the 1960s to the 1980s and, as chair of the CPGB, she endorsed the short-lived Democratic Left project, although it is believed by some that she had private doubts for a period before dissolution about this course.