The Brighton Citizen’s Health Services Survey (BCHSS) was developed to explore and potentially challenge how knowledge is used and by whom in the production of local health commissioning institutions and relations. Through the creation of an ‘animating set of questions’, it sought to open up spaces through which to make visible some of the ways of knowing and valuing the NHS and health services that had been minimised through the commensuration practices of post-2012 public engagement. In this way there was a clear agenda to facilitate a form of knowledge democratisation which opened up and validated different ‘health publics’, in order to explore and broaden participative engagement opportunities. The paper provides an account of the project. It considers the theoretical and methodological underpinnings of this example of ‘evidence-based activism’, reflects on the impact of the project on local commissioning and considers the range of controversies that arose as a result of the work. It explores the way that research straddling the boundary between academic inquiry and political activism speaks to the many issues that are prevalent in the changing HE sector as well as NHS privatisation, health commissioning and public sector cuts.