These tunnels were constructed in 1941 at the rear of the Shorts Seaplane Factory, on the esplanade at Rochester. The original tunnels were two large, brick lined vaults, which were used by the company as a workshop area. These were later connected, by a 1,300 ft tunnel, to a series of underground passages, which were constructed as a public air raid shelter. The air raid tunnels contain a number of original stenciled signs, for 'No Smoking' and for toilets, and are formed of two main parallel tunnels with intersecting spur tunnels. Both the factory tunnels and the air raid shelters have emergency escape adits, which exit in the cliff face at regular intervals or lead to shafts with manhole covers on the surface. There is a great deal of interesting WW2 graffiti to be found in the air raid tunnels, including drawings of planes etc. After the war, the tunnels were used by construction company Blaw Knox as storage, and documents from this time can be found scattered around. The tunnels have remained abandoned since the 1990s, when Blaw Knox left, and a housing estate has been built on the factory site. The tunnel system has now been sealed to prevent further vandalism.
I was able to visit the tunnels as part of a organised tour with the Kent History Fourm, with permission of the housing association who own the tunnels, it is unknown whether further visits will be possible.
Entrance passage to the Factory Tunnels