Below Orpington railway station lies a disused bunker; a former WW2 communications hub. Decisions prioritising train movements and allocating resources were relayed from dedicated ‘Control’ telephones to all signal boxes and other strategic locations in the region. Later, the bunker was used by the railway companies, but is now abandoned.
One entrance was located in the subway running underneath the tracks and is now bricked up; the second entrance is located on property owned by Railtrack. There is no public access, but you can see how the bunker looked a few years ago when a special interest group obtained permission to explore the site, and posted a report of their visit on YouTube, which you can see below :