Former Anti-Aircraft Operations Room, Frodsham

Former Anti-Aircraft Operations Room, Frodsham

An Anti-Aircraft Operations Room built around 1951 for the Ministry of Defence to a design drawn up by the Ministry of Works.

The building is constructed of reinforced concrete, fitted with steel blast doors and ventilators. It is square in plan and comprises a two-storey semi-sunken reinforced concrete structure with a central operations and plotting room surrounded on both floors by a circulating corridor. Surrounding this core are control cabins, offices, communications rooms, plant rooms, latrines and dormitories.

Since the building was designed to resist the effects of a nuclear explosion, there are no windows. The only openings in the structure are the two entrances, ventilator grilles, the stand-by generator exhaust and a protruding ventilation flue on the roof above the plant rooms. The main entrance, situated centrally in the south-east elevation, is at ground level. A second entrance in the north-west elevation is at upper-floor level and is approached by a flight of concrete steps set into the slope of the hill. Both entrances have double steel blast doors protected by open-sided concrete blast wall porches. Three round steel ventilator grilles protected by plain projecting concrete drip moulds are situated either side of the entrance in the north-west elevation.

Entry is at the lower-floor level in the south-east elevation into a lobby that functioned as the reception and security room. A dog-leg circulatory corridor gives access to rooms built around the centrally positioned full-height former operations room. All rooms except the boiler, air-conditioning and generator rooms have been given different functions over time. Their original functions included the tactical radar control room, radio-telephony room, telephone-frame room, Other Ranks and Women's Royal Army Corps rest rooms. The operations room well is entered from the circulatory corridor by two doorways on opposing sides and is overlooked by viewing galleries at first-floor level, supported on plain tubular steel columns. The galleries are accessed from the upper floor and on the northern and southern sides are occupied by cabins which retain their curving anti-reflection Perspex windows. The blank south-eastern wall would originally have displayed situation boards and map boards.

The upper-floor corridor is accessed externally from the north-west entrance and internally from the lower floor by five stairways protected by painted galvanised tube and steel mesh balustrades. A series of rooms surround the operations room, including latrines, rest rooms, a NAFFI, civil servants' room, switchboard and various offices. Some original partition walls have been removed and an open dining area occupies most of the south-western side of the upper floor, while the former Women's Royal Army Corps latrines have been converted to a kitchen. The original positions of walls are visible as witness marks on the Marley-tiled concrete floors. Most rooms on both floors retain their original plain wooden doors. The original box ducting for the ventilation system remains intact throughout. The original air-conditioning plant and filtration system is intact, although the boiler and stand-by generator have been replaced by modern equipment.