We often talk about ‘Town Centres’, but defining their location and extent is surprisingly difficult. Their boundaries are hard to pin down and intrinsically fuzzy. Nevertheless, policy makers often speak or act as if their definition was self-evident. The Dutch and later the British governments, for example, introduced very specific policies for them without ever clearly defining what or where they were. In this paper, we propose a simple methodology to predict town centre boundaries and extent. Using a range of micro-geographical data, we test our method for the whole of Great Britain in an attempt to capture all the dimensions of ‘town centredness’ in a 3D surface. We believe this is a contribution in its own right but is also an essential step if there is to be any rigorous analysis of town centres or evaluation of policies directed at them. Our method should contribute to improve not just debates about cities, shopping hierarchies and town centres, but also to other more general debates where people and policy proceed ahead of any clear definition of what are the objects of interest.