This interview investigates the potential impact of private sector engagement in public health by looking at a working example; the Public Health Responsibility Deal in England (from now on referred to as ‘the Responsibility Deal’). Specifically, it analyses the Responsibility Deal calorie reduction pledge; its stakeholder representation, working practices, and development and implementation, in order to identify the role and influence of the private sector. Martin Caraher is professor of food and health policy at Centre for Food Policy at City University, London. He has worked for and acted as a consultant to the UK Dept of Health, the World Bank and the World Health Organisation. He was a trustee of the Caroline Walker trust. He was a member of the original London Food Board which developed the food strategy for London. He was a member of the Olympic Food Group representing public health interests on behalf of public health in the region. He also sat on the South East Food and Public Health Group which developed a food strategy for the SE region and from which the London food strategy emerged. He currently acts as an advisor on food matters to a number of social science research groups across Europe, as well he is an advisor to the European Executive Agency for Health and Consumers (DG Sanco). He is a member of the International Obesity Task Force (IOTF) scientific committee. He sits on the safefood Irl scientific committee, which is an all -Ireland body set up under the terms of the 1998 Good Friday Agreement.