A new exhibition is revealing the secrets of how London's Underground system kept people safe during World War Two.
The 'Hidden London' display at the London Transport Museum is showcasing how disused stations and tunnels protected people from enemy bombs, including then-prime minister Sir Winston Churchill.
Down Street station, once on the Piccadilly Line in Mayfair, was a bunker for the wartime leader and his cabinet once London's air raid sirens were sounded.
Deep underground, the station, which was closed to the public in 1932, acted as a secure, top-secret bunker.
The Executive Mess room at Down Street where Mr Churchill stayed has now been recreated.
"This was a location that was 22 metres underground," said Chris Nix, who works at the museum.
"It was safe from the bombs that were falling in 1940 and 1941, and [Mr Churchill] could stay here safely and continue his important work as the prime minister and the figurehead of the British war effort."
A telephone exchange box used by operators at Down Street to communicate with other stations is also on display.
The exhibition also looks at the Plessey aircraft factory, located in the tunnels of the Central Line during the war.
The factory employed 2,000 members of staff, mostly women, and was able to keep them safe deep underground.
"Having the facility in there, protected from aerial bombardment was fantastic," said Matt Brosnan, the head curator at the museum.
"A bomb-proof factory where workers and equipment were protected and could work around the clock was utterly vital to the success of the war effort."
The museum says rare wartime pictures are also included in the exhibition, as well as a replica ticketing hall and the living arrangements at some underground shelters.