As attacks on London by the Luftwaffe became a reality in the summer of 1940, Londoners needed somewhere to shelter from the air raids. And so during the Blitz and through to the end of the war, deep-level Tube stations of London underground were utilised, sheltering thousands every night.
But the role of the underground is much more complicated, in 1939, the station platforms were never expected to see civilians sleeping there, but rather they were to be kept clear for emergency transportation use.
In this episode I am joined by Niall Devitt.
Niall is the author of Underground Railway: A New History, which is due to be published by Pen & Sword.