Post-war planning and rebuilding of Britain's towns and cities led to rapid changes in medieval building stock, topography and character, as well as below-ground archaeology. Two case-studies of large, industrial, bomb-damaged yet important former medieval towns are examined in this article: Southampton and Coventry. Together, they illustrate the range of local responses to protecting what we now term the ‘historic environment’ in the period 1945 to 1955 at a time when a limited protection mechanism was introduced through the 1947 Town and Country Planning Act. The responsibility for compiling lists of protected buildings and providing resources to protect them largely fell to local solutions. Using previously unpublished archive material from both national and local sources, this article offers an alternative ‘bottom-up’, local, organized grass-roots viewpoint to most official ‘top-down’ accounts.