Public services are increasingly operating through network governance, requiring those at all levels of the system to build collaborations and adapt their practice. Agent-focused implementation theories, such as ‘street-level bureaucracy’, tend to focus on decision-making and the potential of actors to subvert national policy at a local level. While it is acknowledged that network leaders need to be adaptable and to build trust, much less consideration has been given to the requirement for skills of ‘diplomacy’ needed by those at the front line of delivering public services. In this article, drawing on theoretical insights from international relations about the principles of ‘multi-track diplomacy’, we propose the concept of street level diplomacy, offer illustrative empirical evidence to support it in the context of the implementation of public health (preventative) policies within primary care (a traditionally responsive and curative service) in the English NHS and discuss the contribution and potential limitations of the new concept. The article draws on qualitative data from interviews conducted with those implementing case finding programmes for cardiovascular disease in the West Midlands. The importance of communication and adaptation in the everyday work of professionals, health workers and service managers emerged from the data. Using abductive reasoning, the theory of multi-track diplomacy was used to aid interpretation of the ‘street-level’ work that was being accomplished.