Deep beneath the train lines in part of south London lies a warren of secret tunnels that were used as air-raid shelters for up to 8,000 people during the Second World War and will be opened to the public for guided tours, Transport for London (TfL) has said.

Clapham South Station looks like just another stop on the British capital's sprawling underground train network, but 30m below street level lie secret bunkers where people sought shelter from the bombs, TfL said.

"The reason the government was looking at deep level shelters was because of the issue of civilian casualties during the Blitz; in the autumn of 1940 there were some significant casualties. And in January 1941 Bank Tube station took a direct hit killing 56 people. This is 30m underground, 120ft down and was deemed to be a much safer environment to help Londoners get through that terrible time," said Justin Brand, commercial asset management director for TfL.

When people arrived at the station in the early 1940s, they had to show their ticket showing their individual bed number to an air-raid warden, Tfl said. Much of the original signage still hangs on the walls from the days when the bunkers saved lives. Brand said during the time the tunnels were used loudspeakers pumped music into the rooms and dancing and singing would go on into the night.

"There was a lot of camaraderie, a lot of dancing, a lot of telling stories, there were a lot of families down here, many children running around. And it was very difficult to sleep, as you can hear the Tube train is very close by. This sort of proximity of people meant to keep each other's spirits up there was a lot of dancing and singing," Brand added.

After the war, the bunkers were used as a military and civilian hostel, TfL said. The names of some soldiers and their regiments can be seen on the written on the walls inside the tunnels. It was also used as temporary accommodation for immigrants who arrived from Jamaica in 1948, TfL said. By opening the tunnels up to tours, TfL says it hopes to generate money to improve the city's travel network.

Tickets are expected to become available in March and anyone interested in going is advised to register with London Transport Museum's newsletter for future information. (