The conversion of three existing apartments into two high specification duplex penthouses. The project is located in the Mayfair Conservation Area within the City of Westminster, and as well as the necessary Council approvals also negotiated permissions from estate freeholders and building owners. Avenfield House is an existing eight storey building with residential uses on the upper floors and mixed commercial uses on the ground and first floors. The building remained occupied throughout the duration of the refurbishment contract. The architecture and space planning responds to the location by taking full advantage of panoramic views of the London skyline to the east and Hyde Park to the west. Living spaces are located at the highest floor level with large sliding doors opening onto west facing balconies, double height windows on the eastern elevation provide views of London’s principal landmarks. Each penthouse has a master bedroom suite and three other bedrooms, all have individually designed bathrooms and interiors. In addition, the concierge area and existing passenger lift was completely overhauled and upgraded, whilst we found room to install a new lift within the core of the building around existing services.