The Secret Tunnels of South Heighton

The Cipher Offices.  Before & After 2000.


These pictures show the Post-1943 Cipher Offices as found in 1993, and after clean-up by the Friends of HMS Forward.

The white lines that the Royal Navy had painted round the outsides of the post-1943 Cipher Offices are the only remaining evidence of the two stud-built offices and a small store room that stood in the Eastern Gallery. The timber they contained made them an early target for those who sought to liberate desirable materials when the tunnel was abandoned c.1945. The original Cipher Office was adjacent to the Signals Distribution Office but this was deemed inadequate for the increase in traffic that would result from the Normandy invasion. The two offices allowed for segregation of secrecy classification; the smaller office closer to the Eastern Airlock was used for the highest secrecy level messages that would be dealt with personally by officers who would also hand-deliver the plain language content to the intended recipient.


A clandestine picture taken in the Top Secret office, and the floor of that same location in 2002. This shows that there was a small store room between the far wall of this office and the exterior of the Eastern Airlock. The significance of the painted floor area is not known.


The vacation of the original Cipher Office provided an opportunity to remove the typewriters and duplicating machinery from the SDO to provide more space and a quieter environment for the telephones. The hole seen in the intervening wall, originally provided for ventilation and fitted with a grill, was convenient for passing documents to and fro with the grill removed. (Information provided by former SDO crew).


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All illustrations and text on this site are 1941-2021 Geoffrey Ellis, or The Friends of HMS Forward, or Nick Catford.