Anchor Telephone Exchange

Construction of the Anchor Telephone Exchange began in 1953 beneath the streets of central Birmingham as part of a secret government programme to protect Britain’s trunk telephone network from nuclear attack. Officially, the public were told that the works were for a proposed underground railway, a story that continued until the project was declared uneconomic in 1956. By then, however, a hardened underground exchange and tunnel system had already been completed around 100 feet below Newhall Street at a cost of around £4 million.

Named after the Birmingham Assay Office’s anchor hallmark, the exchange was the largest of the three known underground trunk exchanges built in Britain, the others being Kingsway in London and Guardian in Manchester. It was capable of handling around 250,000 automatic telephone calls each day and formed a vital part of the national communications network throughout the Cold War. Designed to continue operating even if Birmingham suffered an atomic attack, the complex was protected by heavy blast doors, sealed ventilation systems and its own independent power supplies. The underground complex extended far beyond the exchange itself. Large tunnels linked Anchor with other telephone exchanges beneath the city, carrying thousands of telephone circuits on cable racks fixed to the tunnel walls. The site included standby generators, workshops, offices, sleeping accommodation, kitchens and a canteen, allowing engineers to continue working underground if the surface became inaccessible. Water was supplied from a 300-foot-deep artesian well, while sophisticated air-conditioning and ventilation systems were installed to keep the equipment operating for extended periods.

Although built to withstand the effects of an atomic bomb, rapid advances in nuclear weapons meant that the exchange was already becoming obsolete by the time it entered service in 1957. Even so, it continued to play an important role in Britain’s communications infrastructure for decades, handling telephone traffic, broadcast circuits and emergency communications across the Midlands. It was placed on standby only once, during the Cuban Missile Crisis in 1962, before remaining in use throughout much of the Cold War. Although the exchange itself has long since ceased its original role, the tunnels beneath Birmingham continue to carry modern telecommunications cables, with water being continuously pumped from the complex due to the city’s rising water table. For many years the site remained covered by official secrecy, and despite occasional press reports, it is still one of the most remarkable surviving pieces of Britain’s Cold War infrastructure.

Link to Subbrit Article.