This study proposes the first major investigation in the UK into the increasing involvement of private companies in carrying out professional spatial planning work formerly conducted by local government. In the postwar era, decisions about urban development were justified with the idea that state-employed planners served a unified public interest. As politically-neutral bureaucrats working in government, they stood above particular interests to serve a common good. Although this 'public interest' justification has long been challenged it remains important for professional practice. However, over the last 20 years organisational reforms (intensified by austerity) have seen some planning functions of the state devolved to local communities, while the role of the market has been expanded with the private sector increasingly delivering planning services. Nearly half of all UK Chartered Planners now work for private firms and the Government seeks to extend private sector involvement. Despite this, there has been little research on the effects of privatisation on professionalism and how the public interest is understood in planning. To fill this gap, we will focus on 3 key areas: 1. The extent and nature of private sector involvement in planning; 2. The implications of this involvement for planners' understanding of their professional role, 3. The consequences of this involvement for traditional justifications of planning activities as in the 'public interest'. The project will use: -archival work to trace how 'the public interest' is understood in planning: undertaking a history of the concept in relation to changing public/private arrangements for service delivery -focus groups, co-produced with the Royal Town Planning Institute, to provide an up-to-date account of the new public and private organisational arrangements for planning in the UK -biographical interviews, to develop reflective discussion among planning professionals on the way that these new organisational arrangements have changed their understanding and practice relating to professionalism and its role in securing the public interest -in-depth case studies of the contexts in which private sector professionals work to explore how ideas of 'professionalism' and the 'public interest' are defined and realised through the day-to-day practices and interactions of various professionals, politicians and citizens involved in local planning. It will answer five research questions: 1. How have the roles of the public and private sectors in delivering public interest planning goals changed over the post-war period? 2. Through what public/private organisational forms is planning now delivered? 3. How have professional planners working in diverse settings adjusted to changing organisational arrangements, what 'professional' work do they do, and how do they define and understand their professional identity? 4. What effects do different organisational configurations have on the ways that planning's contested public interest purposes are defined and realised, particularly in relation to the complexities of place, democracy, and local politics? 5. How can 'public service' professional labour be reimagined as a means of better realising public interest goals, and challenging dominant understandings of what public services can and should legitimately deliver? As the first empirical study of how privatisation is influencing UK planning, the project will make several ground-breaking contributions to knowledge. It will provide academics with an innovative framework for understanding how these profound changes are reshaping what it means to be a 'professional', and the nature of decision-making in the 'public interest'. Finally, it will generate debate about how professionals might better realise the public interest in the future; highlighting the potentials but also the dangers of the commercialisation of public sector work.