Summarises a research which assessed the extent, pattern and financial consequences of permitted development (PD) across England and also looked into office-to-residential PD in England (and, for comparison, in Scotland and the Netherlands). Five local authority (LA) case studies were examined (Camden, Croydon, Leeds, Leicester and Reading ? all local authorities with high rates of PD schemes) to gauge the extent of individual office-to-residential building schemes that have proceeded under PD and the implications on LA revenues, planning and local communities. The full findings of both research projects are published separately by the RICS Research Trust in parallel to this Insights report (see Bibby et al, 2018 and Clifford et al, 2018). The objective of this Insights report is to bring together the key findings from both projects and consider the implications of extending PD in England.