In the last fifty years, the historic environment has become a major factor in the way we think about, build, and live in cities. This thesis will provide a new interpretation of approaches to heritage and conservation during a transformative period in post-war London. It will focus on the planning culture of the Greater London Council (GLC) — in particular the way that historical buildings and cityscapes were or were not conserved. Due to its responsibility for London’s strategic redevelopment from 1965-86, the GLC was a crucial agent in the development of conservation cultures, profoundly influencing the identity of London, everyday experiences and the way we understand heritage today. In the 70s and 80s the GLC swung between municipal Labourism, a Conservative leadership increasingly coloured by neoliberalism, and finally a radical urban left committed to building alliances with local communities. How these political shifts informed the GLC’s engagement with the historic environment, and the ways in which the council simultaneously accommodated and shaped various strands of the conservation movement will be the subject of extended analysis. Focusing on several contentious sites, including Covent Garden, St Katharine’s Docks and Mansion House Square, this thesis will draw upon oral history, contemporary plans, visual sources such as photography and documentary film, and extensive archival materials, to investigate this changing planning culture and wider understandings of the cultural and economic value of the urban past. These major developments will also be used to consider how heritage was understood in this period, and how changing judgements about different aesthetic styles and urban textures meshed with changing ideological positions and economic pressures. These debates and issues have contemporary relevance, and prefigure current discussions about gentrification, unfettered commercial development, the relationship between built heritage and the creative economy, and the preservation of established urban communities.