When World War II broke out, the Central Line extensions to the east had not yet been opened and parts were used as civilian air-raid shelters. One such, known as Gants Hill Subway Shelter was run by Ilford Council and occupied the pedestrian subways beneath the large roundabout at Gants Hill. The central circulating area was not used as this gave access to the Plessey Factory which was contained within the running tunnels themselves.