At the beginning of the war the official policy had rejected the idea of using the London Underground (Tube) system as a shelter. As well as fearing the development of a 'deep shelter mentality' they felt the railways should be kept clear for troop movements, but, at the start of the Blitz, the citizens of London merely bought a platform ticket and began to 'camp out' on the platforms feeling more secure deep underground than in other types of shelter - e.g. Andersen shelters or Morrison shelters in the home. Sheltering in a tube station may have given a sense of security but conditions were hardly attractive. Space was limited and many have spoken of the terrible smell of so many people sheltering in a confined space without adequate ventilation. Many people became territorial about 'their space' leading to frequent arguments. As the War continued platforms filled up and eventually it became necessary to provide canteens and toilet facilities for those sheltering in the stations. Gradually the authorities relented and some 80 stations were officially used as shelters. They did what they could to make them more comfortable, and life underground soon developed its own culture. The Tube housed 177 000 people at its peak.
Though the Tube was dry and insulated from the noise of bombing its safety was sometimes illusory. A high explosive bomb could penetrate 50 feet (over 15m) through solid ground. On 17 September, 1940 twenty people died when a small bomb hit Marble Arch subway ripping white tiles from the walls and turning them into deadly projectiles. The worst incident of all came on the night of 14 October, 1940 when some 600 people were sheltering in Balham Station, some 30 feet (about 9m) beneath Balham High Road, when a direct hit burst the water main directly above and flooded the station. Those not killed by the blast and falling rubble were drowned. A similar incident at Bank Station in January 1941 killed 111 people. Perhaps the most tragic incident took place on 8 March, 1943 when 1500 people were being admitted to Bethnal Green Station to shelter for the night. The sound of Anti-Aircraft Rockets, only recently introduced into the air defences, startled the crowd who pushed forward onto the stairs. A woman with a child or bundle in her arms tripped and people began to fall on top of each other. In the resultant crush 173 people were killed. Other 'hazards' of sheltering in the Tube, though more mundane, were unpleasant. Plagues of mosquitos descended on the warm bodies of the shelterers; lice crawled from head to head; alternate hot and cold blasts of wind raced through the tunnels; people walked into the tunnels to relieve themselves and the stench was sometimes overwhelming. One witness reports: The stench was frightful, urine and excrement mixed with strong carbolic, sweat, and dirty, unwashed humanity.