Previous research has identified political ideology as central in the landmark Academies Act (2010). This article further analyses how politics of evidence played its part in the policy process by focusing on long-term structural changes and preferences among policymakers. The article draws on policymaker interviews after the reform, a mapping of think tanks and a document analysis. The analysis shows that political–ideological preferences were derived from think tanks, and the Conservative manifesto built on skewed Swedish evidence in constructing an argument for the Act. The political choices morphed into fact-based arguments in the policy process. While think tanks had some reservations, in the Whitehall bureaucracy the argument was reformulated as a rational deliberation. This was possible because of the long-term change in the significance of think tanks, and how policymakers preferred politically informed opinions instead of research evidence. The conclusion argues that the evidence-based policy emphasis is an attempt to depoliticise the scope for political arguments. The political dynamic thus results in structurally empowered and layered but depoliticising use of evidence.