Operation

The station is in Down Street in Mayfair, just off Piccadilly and a short distance from Park Lane. It lies between Green Park (originally named Dover Street) and Hyde Park Corner on the Piccadilly line. It was opened by the Great Northern, Piccadilly and Brompton Railway (GNP&BR; the precursor to the Piccadilly line) on 15 March 1907, a few months after the rest of the line opened.^{[2][n 1]} The delay was due to difficulties in purchasing the site for the station building and agreeing a safe layout of the passages below ground with the Board of Trade.^{[3][n 2]} The surface building was designed by the Underground Electric Railways Company of London's (UERL's) architect Leslie Green in the UERL house style of a two-storey steel-framed building faced with red glazed terracotta blocks, with wide semi-circular windows on the upper floor.^[5] The station had a pair of Otis lifts, with the platforms located 22.2 metres (73 ft) below the street level of Piccadilly.^[6]

Down Street was never a busy station, as the surrounding area was largely residential and its residents mostly wealthy enough to travel by other means. The neighbouring stations were also close by, with Dover Street station about 550 metres (600 yd) to the east and Hyde Park Corner 500 metres (550 yd) to the west.^[7] From 1909, like Brompton Road, Down Street was often skipped by trains. From 1918 it was closed on Sundays.^[7]

In 1929, Down Street was one of the stations suggested for closure in connection with the extension of the Piccadilly line: the elimination of less-busy stations in the central area would improve both reliability and journey times for long-distance commuters.^{[7][n 3]} Additionally, the neighbouring stations were being rebuilt with escalators in place of lifts and their new entrances were even nearer to Down Street, further squeezing its catchment area. The station was permanently closed on 21 May 1932.^[2]

After the station was closed it was almost immediately modified. The western headwalls of both platform tunnels were rebuilt to allow a step plate junction to be installed,^{[n 4]} providing access from the eastbound and westbound tunnels to a new siding located between Down Street and Hyde Park Corner. The siding is mainly used to reverse westbound trains, but could also be used for servicing trains. The siding tunnel is accessible at its western end through a small foot tunnel constructed from Hyde Park Corner station.^[8] The lifts were removed and the shafts adapted to provide additional tunnel ventilation.^[9]

Wartime use and after

The station was selected for use as an underground bunker in early 1939 as part of a programme of developing deep shelters to protect government operations from bombing in the event of war.^[9] The platform faces were bricked up and the enclosed platform areas and space in the circulation passages were divided up into offices, meeting rooms and dormitories.^[10][11] The engineering and structural work was carried out by the London Passenger Transport Board and the fitting-out of the rooms and installation of the power and communications equipment was done by the London, Midland and Scottish Railway.^[10] A two-person lift was installed in the original emergency stairwell and a telephone exchange, toilets and bathrooms were added.^[9] The main occupant of the shelter was the Railway Executive Committee,^{[n 5]} but it was also used as a shelter by the Prime Minister, Winston Churchill, and the war cabinet until the Cabinet War Rooms were ready;^[12] Churchill called it "The Barn".^[12]

Since the end of the war, the station has been used only for engineering access and as an emergency exit point from the Underground.^[9]

In April 2015, Transport for London announced that it was seeking proposals for the commercial use of parts of the surface building, disused lift shaft and underground passages.^[13] Suggested possible uses included a restaurant, a bar, a theatre, a gallery or retail space.^[14] Tours by the London Transport Museum through its "Hidden London" programme began in 2016.^[15]