After the station was closed it was almost immediately modified. The western headwalls of both platform tunnels were modified to allow a step plate junction (a junction where tunnels of differing diameters join—the step is the vertical wall filling the gap between them) to be installed, providing access to a new siding located between Down Street and Hyde Park Corner stations. In 1939, the platform faces were bricked up and the resulting space used as an underground bunker. The main wartime occupants of the station were the Emergency Railway Committee, but it was also used by Churchill and the war cabinet until the Cabinet War Rooms were ready for use. Since the end of the war the station has only been used as an emergency access point to the tube. The surface building, designed by Leslie