War Room Bunker

War Room Bunker, Mill Hill

This is an exceptionally well-preserved War Room from the early 1950s, built as reinforced concrete construction. The building comprises a two-storey surface structure centred on a map room surrounded by control cabins, offices and a plant room. The elevations are plain, with a projecting parapet to the flat roof and steel doors at the entrance. Three protruding ventilation and exhaust structures sit on the roof along the eastern edge, each a box-like form approximately 1.5 metres by 1 metre in plan and 1.5 metres tall, constructed in concrete or render with black louvres in several faces.

The central planning room is ringed by wooden-framed windows connecting to the surrounding suite of rooms. These windows have fabric mesh instead of glass, with one opening frame in each to allow passage of documents. The surrounding rooms retain their original wooden doors, painted red like the main entrance blast doors, with white room numbers marked at eye level. Both main entrances feature twin doors: a wooden outer door with metal sheet reinforcement and standard locks, and a substantial inner blast door set along each passage and fastened from within by two locking levels.

Most rooms retain their original light fittings—single bulb fitments covered by inverted glass domed cylinders—attached to original metal tube conduits for wiring and original metal light switch boxes. Metal coat hooks mounted on wooden battens and the original box-ducting for the ventilation system survive throughout.

Two complete lavatory and shower rooms, one male and one female, contain shower stalls, hand basins, toilet cubicles and pedestals, and hot water tanks (twin sets of immersion-heated tanks the size of domestic units in each). Fresh water tanks in riveted painted steel, each approximately 1.5 metres square, occupy small rooms adjacent to each shower room, with a further water tank room on the southern corridor.

The oil-fired engine for the electrical plant survives intact, dated 1953 on its manufacturer's plate, together with the electrical plant itself including AC transformer, junction boxes and regulators. The fan system for internal ventilation is substantially intact in an adjacent room, complete with baffle and filter chamber and the main duct leading to the rest of the system, fitted with summer and winter flow controls.

This War Room was one of twelve bunkers built in the early 1950s to protect Regional Commissioners and their staff of around 50 people from atomic bomb attack. From the 1920s, Britain had been divided into twelve Home Defence Regions, each controlled by a Regional Commissioner in case of emergency. Initial protection came from existing government offices or improvised basement shelters, but the arrival of Soviet atomic weapons prompted the construction of purpose-built bunkers. Of these twelve, only the examples at Brislington in Bristol and Mill Hill survive, with Mill Hill being the sole survivor of four bunkers originally serving London.

The form of these War Rooms—a central operations room surrounded by control cabins supported by communications rooms, air conditioning plant and emergency generators—was a new type of architecture in Britain, designed specifically to counter the effects of nuclear weapons. They embody the fear of nuclear annihilation that defined much of the Cold War and connect directly to the wider Cold War infrastructure built following the Soviet atomic detonation in 1949, the Korean War and deteriorating conditions in eastern Europe, including USAAF bases, Rotor radar bunkers and missile bases.