The recent move of public health back to English local government has reignited debates about the role of a medicalised public health profession. The explicit policy rationale for the move was that local government is the arena in which the social determinants of health can be addressed, and that public health specialists could provide neutral evidence to support action on these. However, if a discourse of 'evidence-based' policy is in principle (if not practice) relatively unproblematic within the health arena, within the more overtly politicised local government space, rather different policy imperatives come to the fore. Responding to calls for research on evidence in practice, this article draws on ethnographic data of local authorities in the first year of the reorganised public health function. Focusing on alcohol policy, we explore how decisions that affect public health are rationalised and enacted through discourses of localism, empiricism and holism. These frame policy outcomes as inevitably plural and contingent: a framing which sits uneasily with normative discourses of evidence-based policy. We argue that locating public health in local government necessitates a refocusing of how evidence for public health is conceptualised, to incorporate multiple, and political, understandings of health and wellbeing.