In the 1940s the Marxist mathematician and historian of science Samuel Lilley (1914–87) made a substantial contribution to British history of science both intellectually and institutionally. His role, however, has largely gone unnoticed. Lilley is otherwise portrayed either as exemplifying the immaturity of Marxism, most famously by Rupert Hall in ‘Merton revisited’ (1963), or as a tragic figure marginalized during the Cold War because of his communist commitment. But both themes of exclusion and victimization keep Lilley's legacy hidden. By revisiting Lilley and his long-standing commitment to developing our discipline, this essay challenges the notion of radical discontinuity with respect to Lilley's legacy and argues for a more sustained contribution by Marxist historiography of science. This, in turn, requires a more appreciative understanding of the moderate Marxist model developed by Lilley in his popular, political and professional publications on the history of the social relations of science.