There has been a significant growth in the number of subterranean residential developments over the past 10 years in the UK, particularly within London. While they may present little visible evidence above ground, such developments can have significant impacts on sustainability, amenity and environmental quality. Nevertheless, few local planning authorities have developed specific policies in response to such developments. This article outlines the results and implications of research that investigated the approach of four London local planning authorities to such development, with a particular focus on the Royal Borough of Kensington and Chelsea, which has developed more detailed policy for subterranean development than any other authority. The article suggests that more effective outcomes for sustainability, amenity and environmental quality could be achieved by more general application of policy for subterranean development, with implications also for contexts outside the UK. © Taylor & Francis.