A key current concern is how scientific knowledge may inform policy in relation to major environmental and health concerns. There are distinct schools of analysis about this relationship between science and policy. They stress rational relationships; denial and delay; or the role of networks. History is important in modifying such perspectives: smoking policy in the 1950s and 1960s is the case study here. The initial response in the 1950s to the link between smoking and lung cancer was in part conditioned by the role of the tobacco industry and the financial importance of tobacco: the British tobacco industry had closer relationships with government than the American one, and did not rely on public relations. Public health interests worked with the industry. But politicians were concerned also about the fluidity of the epidemiological evidence; the dangers of stirring up further pressure over air pollution; the financial and ideological implications of health education and its location; and the electoral dangers of intervening in a popular mass habit. In the 1960s the British and American medical reports stimulated the growth of a public health ‘policy community’. The initial political considerations began to weaken and these years marked the beginning of a new style of public health.