Joan Simon (née Peel, 1915-2005) was the life-long partner of Brian Simon who helped launch FORUM in September 1958. Like Brian, she embraced a Communist outlook and engagement in the area of education. Unlike Brian, she practiced the historian's craft outside the male academic hierarchy. Based on newly available personal papers this study sprang from my interest in the role of gender in the formation and dissemination of British social science, which I take to include the beginnings of economic and social history. Here the author draws attention to the scholarship and social action of Joan Simon to show how the production of new social knowledge helped shape the development and organisation of comprehensive education. The article is part of a larger project exploring the historical connections between university-based research and reformist efforts in the expanding and partially overlapping worlds of social studies and social action in the nineteenth and twentieth centuries.