It seems incredible in these days of the internet, mobile phones and other forms of instant, mass communication that the violent deaths of 68 people could be effectively covered up for five years.

But in October 1940, when a bomb tore through the water and gas mains in Balham, flooding the town's tube station and drowning scores of people sheltering there, a news blackout was indeed imposed, and it was surprisingly effective.

The propaganda war was deemed almost as important as the military war, and it was felt that if the tens of thousands of people using tube platforms throughout London felt their havens were not impregnable the result could be widespread fear and possibly panic.

Better by far for the co-operative newspapers of the day to report tales of bravery and British stoicism.

One slogan was "Britain Can Take It", and photographs of the numerous casualties were buried a patriotic collusion impossible to envisage now.

The fact was that tube stations sheltering 177,000 people at their peak were not as safe as people believed.

High explosive Luftwaffe bombs could penetrate up to 50ft through solid ground, and although Balham was the scene of the worst tragedy, 20 people had died at Marble Arch just a month before, and other stations were targeted too.

The Government at first tried to discourage the use of Underground stations during air raids: not only for safety reasons but because they wanted railways to be kept clear for troop movements.

But it had to relent when Londoners simply began buying tickets and camping out on the platforms.

There were 600 people in Balham station on the evening of October 14, 1940. It was not a pleasant place to spend long hours.

Apart from the ever-present fear of a direct hit, tube platforms were not hygienic.

People would urinate in the tunnels and the close-packed crowds were reportedly a playground for lice.

At 9.15pm Balham's putrid tunnels instantly became something much worse: a deathtrap.

A direct hit devastated the junction outside the station, severing water and gas mains, fracturing a sewer and fusing the lights.

Water deluged the northbound platform within minutes, sweeping an avalanche of rubble and sand onto the people sheltering there.

Hundreds escaped, but many were stranded, and a remarkable rescue attempt was made by floating a boat along the flooded tunnel from Clapham South station.

But the effort was in vain, and 68 people, including four station staff, lost their lives.

It was not until Christmas that the last body was recovered, and not until January 1941 that the station was back in use.

Covered up at the time, the disaster, and the lives of those lost, are now commemorated by a plaque in the ticket hall of the station.

But there are other, more subtle legacies of those Balham residents' deaths that your eye may linger on unwittingly when waiting for a train or when passing other stations.

One is the presence of heavy concrete block houses at the heads of staircases in stations along the Northern Line, built to avoid a repetition of the tragedy.

More subtly, modern commuters may notice a lack of trackside tiling at the northern ends of Balham's platforms an oversight from the station's post-bomb reconstruction, and a detail that, when known, cannot fail to evoke images of the night of October 14, 1940, until your train screams into the station, swallows you up and carries you safely away.

January 30, 2003 11:00