Brian Simon (1915-2002), an influential Marxist historian and educationist in Britain, had been campaigning for comprehensive education from the late 1940s to the 1960s. In the early 1970s, followed by a rapid expansion of comprehensive schools since the issue of Circular 10/65, comprehensive education was under attack by the Conservative government and other conservatives. In the mid-late 70s, along with the conservatives and the New Right, left-wing intellectuals also undermined the public's confidence in comprehensive education. Faced with the crisis in comprehensive education, Simon continued to battle for it by shifting between different roles. Simon was not only involved in politics of education, but also dealt with ideological issues implicit in contemporary educational theories nationally and internationally which caused harm to comprehensive education. Despite this, very little research has focused on Simon's ideas and practice in relation to comprehensive education in the 1970s. Therefore, this paper aims to fill the lacuna.