London’s Secret Tubes and Secure Communications Beneath the Streets

I had some time to kill at the Toronto Reference Library last week, and I was lucky enough to browse my way along to London’s Secret Tubes by Andrew Emmerson and Tony Beard. The book doesn’t circulate, so I wasn’t able to finish reading it, but it is chock-full of remarkable information about the military and civilian services that operated underground during World War Two and the Cold War. As well as covering the various headquarters that were built to resist aerial bombardment (like the Cabinet War Rooms, Admiralty Citadel, and the alternate Cabinet war room code-named PADDOCK) and the deep air raid shelters, London’s Secret Tubes discusses a lot of the communications infrastructure that was buried for protection. The British telephone system’s main exchange was in Central London, so the Post Office (who operated it) not only built an alternate connection in the suburbs but also add a ring of alternate connections that skirted the city so that calls could be rerouted around the edge if connections to the hub were broken. After the war the central interchange itself went underground, taking over the deep shelter beneath Chancery Lane as the Kingsway exchange (on which more here).

Most of a SIGSALY installation (at the National Cryptologic Museum

Most of a SIGSALY installation (at the National Cryptologic Museum)

London’s Secret Tubes isn’t a book about communications networks per se, but discussing the hardening to them makes it an inadvertent guide to just how many systems were operating in and through London. In addition to the telephone system, the undersea cables headed overseas – for telegraphy at this stage, not telephones – had their British final connections in central London. These too had to have backup connections in the suburbs, often in converted private homes. The British end of the encrypted voice radio link between Churchill and FDR was also in London, installed in the basement beneath Selfridges department store – which Emmerson and Beard report was only one of several department stores taken over by the government during the war.

Though incredibly important, these networks were less of a “system of systems” and more of an accretion of communications systems that gravitated towards the centers of economic and political power. And, from time to time, they hit their limits. My favourite example is one that historian Peter Hennessy shared in a 2009 lecture (paywalled here) and incorporated into the revised edition of his book Secret State. In 1962, when the British government was tracing out the communications links the prime minister would use in case of an imminent nuclear attack, the connection to be used if the prime minister was in a car was a radio broadcast from the system the Automobile Association (the UK equivalent of AAA) used to contact its service patrols. The prime minister would then make for the nearest phone booth to call Whitehall. Should the driver not have change for the phone call (an issue which really did come up in planning), the prime minister would simply reverse the charges and make decisions of national security via a collect call. The mind boggles.

(I’m not going to reproduce the communications diagram that includes the AA radio link, since it’s Crown copyright and would require permission [and a payment to get a clean copy], but you can see it at a good size on The National Archives website here. The AA link is in the top right corner, complete with a little drawing of a car. The file itself is DEFE 25/49 (1),”Nuclear retaliation procedures.”)

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