One of the largest and most complex projects undertaken by Ptolemy Dean Architects has been the reorganisation of the Busby?s Yard buildings at Westminster School. These are former medieval abbey precinct buildings now knitted together and integrated into the busy life of a working school. Listed Grade I, these buildings lie within the Westminster World Heritage Site, and are about as sensitive as can be. Rather than simply adding further structures in and around these existing buildings, we began a process of selective additions to their rooftops, allowing later accretions to be removed and the formerly historic yard area to be regained. Ultimately it is these wonderful outside courtyard spaces that give the school its unique and historic precinct atmosphere, while the process is allowing much of the historic interest and value to be recovered in the buildings themselves. The works at the School were split into 5 phases, in order to fit around the busy School calender and avoid unnecessary disruption to the working of the boarding School. The project has involved the clearing of mid-C20th additions from Busby?s Yard (started in Phase I and completed in Phase V), the addition of roof top extensions to two boarding houses to provide additional accommodation (Phases II and IV), the creation of a new housemaster?s flat within an existing attic space (Phase II), the creation of a new School reception area (phase III), and improvements to the School?s staffroom accommodation (Phase V).