The Northern line is about 120ft feet below the ground at Clapham South, so it’s hard to conceive of anyone being woken up by its trains.
That was the alarm call, though, for almost 300 people who lived in tunnels 180 steps below the surface in 1948.
They were immigrants from the colonies of the Empire who had come to London to help rebuild Britain’s industry and power following the Second World War.
They had arrived 70 years ago on the SS Empire Windrush, some in the first wave.
It must have been fun to start off with, living cosily a long way below the bustle of the city, almost like being in a tent on holiday, with primitive facilities and creaking bunk beds, and nothing for entertainment apart from board games and a hearty singsong.
But one climb of those 180 steps to get to work on a bleary morning was enough to put most of them off. The majority stayed three weeks – and the longest stopover was a month.
The cavernous, elongated tunnels open to the public again in August – but this time they are not for living in.
That was banned after a fire inside a similar warren in Goodge Street in 1956 saw the end of their use as dormitories forever.
They had been used for short-stay visitors in the run-up to the funeral of George VI on February 15, 1952, and then again for the coronation of his daughter, Queen Elizabeth, on June 2 1953.
That was the last time they were used for overnight stays. The tunnels were used for storage of Government papers until 1998, and then handed over to London Transport – the only body able to handle the maintenance of such structures.
The London Transport Museum took them over in 2008, with no drawings or maps, and precious little knowledge of any kind of what was down there.
The first visitor must have felt like a modern-day Theseus. The semi-mythical adventurer used a ball of wool to find his way in King Minos’ maze. Luckily for the staff, they found no Minotaur down there – just rusting beds, a few of the original signs… and a lot of dust.
All those – including a bit of the dust – can be seen on the tours which start down there in August.
Around 236 migrants from the merchant vessel, which first arrived on June 22, 1948, were housed in the labyrinth of underground passages at Clapham South when they first arrived from the former British colonies.
These immigrants from the West Indies helped to rebuild Britain after the war when there were labour shortages in housing, transport and hospital work.
This makes the tunnels a vital part of the UK’s diverse history.
The tunnels were also used for civilian sheltering during the Second World War and as budget hotel accommodation in the post-war years during the Festival of Britain in 1951.
The lack of housing after the Second World War meant that accommodation for British citizens from the Caribbean was in short supply.
When the authorities became aware that more than 200 migrants had nowhere to stay, Clapham South was used as a short-term residential base for them until they could find their own homes.
Within four weeks of arriving, all the Windrush migrants had moved out of the site.
London Transport Museum is reopening them to the public this month.
In partnership with the Windrush Foundation, they invited John Richards, 92, to return to the Clapham South Subterranean shelter he had lived in for three weeks when he first arrived in London after the SS Empire Windrush ship had docked at Tilbury.
Mr Richards said: “The trains that ran overhead in the morning woke me up. There were beds all around with crisp white sheets.
They had a tea cart at the station… pie in the evening.”
After leaving the Clapham South shelter, Mr Richards moved to a hostel and then found work at British Rail.
“I survived, because friends know friends. It was hard but in the long run you find a way,” said Mr Richards.
South London residents and readers of the South London Press can obtain a discount of 25 per cent if they use the following code SLP25 when booking online at www.ltmuseum.co.uk/hidden-lond
Tickets are now on sale for tours starting on August 11, and run on Wednesdays to Sundays. Tickets for adults cost £38.50 and concessions are £33.50.
To book email firstname.lastname@example.org or call 0207 565 7298.