Pensions are a controversial issue in Britain. During the past fifty years, pension reforms have been challenged by the competing policies of the Conservative Party and the Labour Party. There were differences in the nature, scope and extent of pension policies between them: the Conservatives encouraged private pension provision while the Labour Party promoted state provision. Based on core principles of freedom and personal responsibility, the Conservatives persistently over time implemented policies in line with these beliefs. This article explores this transformation of the post-war pension regime. An attempt is made here to sketch out a new explanation of this transformation in drawing on recent theories of the role of ideas and ideology in the policy process. The recent apparent convergence in policy thinking on pensions between the Labour Party and the Conservative Party highlights the importance of core ideological principles.