Kingsway telephone exchange

In 1949 the General Post Office (GPO) took over the building, and in 1956 it became the UK termination point for TAT-1, the first transatlantic telephone cable.

[1][2] The Kingsway telephone exchange was built as a deep-level shelter underneath Chancery Lane tube station in the early 1940s, consisting of two east–west aligned tunnels, one on each side of the Central Line.

After the exchange was wound down the site was used for the Radio Interference Investigation Group, whose function was to prevent television viewers and radio listeners in north and central London from suffering interference to their service from external sources such as thermostats, fluorescent tubes and injection moulding equipment.

The site contained an artesian well and rations to maintain several hundred people for many months, to try to ensure a safe environment in case of nuclear attack.

Subject to planning approval, working with architect WilkinsonEyre, The London Tunnels' vision is to create an interactive cultural experience, with an operational capacity of two million visitors per year.

[4]: 146 The Exchange features in the third of James Herbert's The Rats trilogy Domain, as a place where survivors of a nuclear attack on London take shelter.

[12] Once home to MI6's Special Operations Executive, the tunnels are referenced by Ian Fleming (who worked as an SOE liaison officer) in his first James Bond book Casino Royale as the location of M's Q Branch laboratories.