In anticipation of the coming conflict, Erith Hospital built an underground Field Hospital Casualty Station in 1938. It is protected by earth piled on top of its concrete roof, where plants and even trees provide some degree of camouflage. Although it had only limited usage during the conflict, it was staffed throughout the war.
The facility originally had separate entrances for men and women and its extensive layout provided essentially mirrored facilities. Disused after the war, in 1950 it was reourposed as the X-Ray Department, a function it still performs today. So to some extent the facility can be visited but only by those in need of medical X-Rays.