Building 33 (Station Headquarters)

Building 33 is an office block that originally served as the station headquarters building at RAF Biggin Hill. It was constructed in 1931 to Air Ministry Directorate of Works drawing number 1329/27. The building is constructed of red brickwork in stretcher bond with cavity walls, has a slate roof, and features leadwork to the flat roof section.

The building has a central hall and staircase leading to a corridor with double-banked offices on each floor. It forms a symmetrical two-storey rectangular block with hipped roofs and a short central projection to the rear with a flat roof. This continues as a single-storey structure with a double hipped unit forming a central valley. The original accommodation included offices for the Commanding Officer and engineering staff, an accounts section, waiting and orderly rooms, a lecture room, and a library.

The front elevation is two storeys high with nine windows across. The windows are timber glazing-bar sashes set into slight reveals with brick voussoir heads and concrete subsills. The central three bays project forward and feature a brick parapet rising above the continuous eaves-line. Most windows have plain bottom sashes with six-pane upper sashes, though full twelve-pane sashes have been inserted later in bay 4 at ground floor level and bay 9 at first floor level. The main entrance consists of a central pair of three-panel doors approached by two steps, framed within a Portland stone surround. This surround features a fine moulded architrave, plain pilasters on block bases, and modelled brackets supporting a heavy plain cornice with a flat top and moulded edge. The frieze between the brackets is inscribed 'AD 1931'.

The end returns are arranged in two bays, with all windows having plain lower sashes. The rear elevation has windows with three-over-one panes on each side of the projecting flat-roofed section. Those to the left have twelve-pane upper sashes at first floor level, while those to the right also have twelve panes at this level. At ground floor level, these windows have only single lights. The flat-roofed projection features a replacement light above the door and a small four-pane window to the right, with a sash window having a plain lower light at each level to the left. The rear wall has a central small light positioned to the left of a square chimney stack with brick capping. The double single-storey range has four twelve-pane windows to the long sides.

A fascia with an ogee gutter on a small soffit to a bed-mould runs completely around the main block. Centred on the ridge is a square wooden turret with louvred sides and a flat square leaded cupola. Above the entrance is a short flagstaff rising from gutter level and braced to the parapet.

Inside, the building retains its original joinery with panelled doors. The staircase is of dogleg form with a steel balustrade.

The building is located at the south end of the domestic site in West Camp, opposite the former Officers' Mess. It is a characteristic example of early Expansion Period architecture and remains externally almost unchanged except for a small number of replacement sashes. It was the first building to be reoccupied after the devastation of West Camp during the Battle of Britain.

Biggin Hill acquired a reputation as the most famous fighter station in the world, primarily through its associations with the Battle of Britain – the first time in history that a nation had retained its freedom and independence through air power. It developed as a key fighter station during the inter-war period, playing a critical role in developing the air defence system based on radar that proved crucial in the Second World War. Of all the sites involved in the Battle of Britain, none have greater resonance in the popular imagination than the sector airfields within 11 Group, which bore the brunt of the Luftwaffe onslaught. In Churchill's words, these were the stations 'on whose organisation and combination the whole fighting power of our Air Force at this moment depended'. 11 Group, commanded by Air Vice Marshal Keith Park from his underground headquarters at RAF Uxbridge, occupied the front line in the battle. Its sector stations at Northolt, North Weald, Biggin Hill, Tangmere, Debden and Hornchurch took some of the most sustained attacks of the battle, especially between 24th August and 6th September 1940, when these airfields and later aircraft factories became the Luftwaffe's prime targets.

Biggin Hill opened as a military landing ground in February 1914. From 1917 it functioned as a Radio Signals Unit and from February 1918 as a Home Defence Aerodrome as part of London's air defence system. The first substantial group of buildings was erected on South Camp in 1917, when 80 acres were acquired from the Earl of Stanhope's estate. Only fragmentary remains date from this period. The significant surviving buildings, mostly from 1930-31, are located further north in West Camp, situated on each side of the main Bromley to Westerham road (the A233). Work on rebuilding the station in permanent fabric began in 1929, with several buildings bearing datestones of 1930 and 1931. The Air Estimates for 1933-34 show that £190,000 had been allotted for this purpose. The surviving buildings are mostly representative of the type designs associated with Trenchard's Home Defence Expansion Scheme from 1923 onwards, with the principal exception being the Officers' Mess.

Biggin Hill had been the subject of pioneering air-to-air and ground-to-air experiments in radio communication and, crucially, in integrating radar into an operationally successful fighter defence system. During the critical Biggin Hill Experiment of 1938, the station was used as a laboratory for creating the Fighter Direction organisation, linking radar to defending aircraft. The 1930s also saw Biggin Hill functioning both as a weather-reporting station on the Croydon-Le Bourget route and as a relief airport for Croydon.

The runways, perimeter track, and twelve blast pens were constructed on an enlarged airfield as part of Dowding's drive to provide dispersed and serviceable flying fields on Fighter Command's front-line bases in 1939, with the runways completed in March 1940. One intact and two partially surviving blast pens survive in the north half of the site, along with some pillboxes and a hydraulically operated Pickett Hamilton fort. The runways form a 'V' rather than the more typical plan, partly due to the constricted nature of the site. These were augmented by a 1,700-yard runway extending to the north, begun in March 1942.

Few buildings have been demolished on the technical site since 1945, and the existing gaps date from the raids during the Battle of Britain that caused such damage and loss of life. The raid of 30th August 1940 resulted in considerable loss of life (39 dead and 26 wounded) in addition to severe damage to the barracks, WAAF quarters, workshops, stores, and an F-type Admiralty hangar. On the following day the Sector Operations Room took a direct hit and other hangars were badly damaged. On 6th September, after further raids had rendered much of the base unusable, the last surviving hangar was destroyed on orders of the base commander. With attacks switched to London throughout the autumn Blitz, there was some respite, but there was a prolonged daylight attack on the morning of 2nd October, and four days later another raid demolished three of the barracks blocks. Tangmere Block (Building 1) retains evidence of that period, when its left wing was damaged and reduced from two storeys to one. Several units of the married housing in Vincent Square were also destroyed.

Biggin Hill's location south of London guaranteed its front-line involvement in fighter operations throughout the Second World War, from the Battle of France to support of daylight raids by Bomber Command. In addition to sharing with Hornchurch the distinction of being the most bombed aerodrome in Fighter Command, it was regarded as Britain's principal fighter station. More enemy aircraft (1,400, including the first thousand by 1943) had been destroyed by squadrons based at Biggin Hill than at any other airfield, and its aces – including Michael Crossley, 'Sailor' Malan, Mungo Park, A.C. Deere, Max Aitken, and Brian Kingcome – became national figures, as did volunteers of the Free French and U.S. Eagle squadrons. 453 aircrew were killed while operating from Biggin Hill.

Biggin Hill's satellites were West Malling and Manston, with the former customs airport at Lympne serving as a landing strip. Like Kenley, it was sited within the balloon barrage erected around London as part of Operation Diver between spring and October 1944. The main runway was extended in 1957 for Hawker Hunter jets. The RAF ceased flying in 1959, after which the runways were transferred to civil control, and withdrew from the site in 1992. Following this withdrawal, and amid fears concerning the future of the site, Bromley Borough Council, with strong support from English Heritage and veterans' associations, designated the technical site and the former married quarters as a conservation area. The technical site is now mostly in the ownership of Formula One, and the married quarters – the best-preserved group of their type noted in the thematic survey – have been sensitively developed for private housing. The former flying field is now used by Bromley Civil Airport.