This article explores the relationship between ideas and interests in policy change by examining tobacco control in each country of the United Kingdom (UK). In all four, the moves towards further prohibition reflected international trends, with evidence of policy transfer and the virus-like spread of ideas which has shifted the way that tobacco is framed. However, there are notable differences in the development of policy in each territory. This reinforces conceptions of transfer in which the importation of policy is mediated by political systems. Differences in policy conditions, institutions and 'windows of opportunity', mean that our conclusions on the role and influence of interest groups, institutions and agenda-setting vary by territory, even within a member state. This suggests that a focus on an 'idea whose time has come' should be supplemented by careful analysis of the political context in which the idea was articulated and accepted.