Neighbourhood planning in the UK is a striking example of the international turn to localism and public participation, the statutory weight afforded to it setting it apart from many other initiatives. Its promoters portray it as a straightforward transfer of power from state to community. However, its legitimacy relies upon complex, hybrid forms of representative, participatory and epistemological authority. A growing literature is interrogating the relations between neighbourhood planning groups – the collectives utilising these new powers – and the neighbourhoods for which they speak. This paper brings empirical evidence forward to build on such work by exploring how the identities of neighbourhood planning groups are constituted. Three different and sometimes conflicting relational identities are characterised. Each identity is associated with particular material relations, types of knowledge and ways of representing the neighbourhood, and consequently produces different forms of legitimacy. Analysing identities in this way aids understanding of the practices through which legitimacy is achieved in experiments in democracy that rely on hybrid forms of authority. It may also open possibilities for intervention that speak to some of the concerns raised in the literature about these hybrid forms.