Operations Block, Carver Barracks (Former Raf Debden)

Building Description

This is a sector operations block constructed in 1938 to designs by J.H. Binge of the Air Ministry's Directorate of Works and Buildings (drawing number 5000/137). The structure employs reinforced concrete with Flemish bond brickwork cladding. Its distinctive roof construction consists of a thick-section concrete sub-roof slab supported by 20 large-scale rolled steel joists, with sand and shingle filling the 4 feet 6 inch space between this and a thin-section concrete upper roof covered in asphalt.

The building comprises a tall block with a projecting section on the north elevation, positioned to the north of a wider and lower south section which itself projects at the east end. The plotting room occupies the major space in the taller northern block, whilst other rooms include the operations room, meteorological office, battery room, ventilating plant room, searchlight room, teleprinter room, traffic office and receiving room.

The building is surrounded by a 9 foot high reinforced concrete traverse wall with a maximum thickness of 17 feet to its angled earth bank, designed to protect against incendiaries and bomb blast. Angled entrances with shuttered concrete lining are located on the west elevation and in the north-east angle next to the east projection of the south range. The south range features four timber casements with cast-iron grilles on its south elevation and one on its east elevation. Cast-iron rainwater goods are fitted throughout, and ladder stairs provide roof access on the west elevation.

The interior survives in remarkably intact condition, retaining original joinery including doors to message hatches, twin safes in the Code Room, cast-iron furniture to timber doors, electrical face plates, and ducting and grilles serving the air filtration plant. Steel outer doors remain in place. A raised platform runs along one side of the plotting room, providing a view of the centre of the room where radio cross-bearings of Sector aircraft were translated into map positions before being passed to the operations room. Shuttered openings survive between the operations room and wireless cabinets, whose operators maintained contact with sector fighters and on demand switched the radio-telephone through to the controllers or his assistants.

Historical Context

The airfields associated with the Battle of Britain of 1940—when Britain became the first nation in history to retain its freedom and independence through air power—relate to historic sites and fabric stretching from those used by the Royal Air Force to those used by or built especially for the Luftwaffe, including the now-protected sites at Paris Le Bourget and Deelen in the Netherlands. Of all the sites involved in the Battle of Britain, none have greater resonance in the popular imagination than the sector airfields within the Groups which bore the brunt of the Luftwaffe onslaught and, in Churchill's words, 'on whose organisation and combination the whole fighting power of our Air Force at this moment depended'.

It was 11 Group, commanded by Air Vice Marshall Keith Park from his underground headquarters at RAF Uxbridge, which occupied the front line in this battle. Its 'nerve centre' sector stations at Northolt, North Weald, Biggin Hill, Tangmere, Debden and Hornchurch took some of the most sustained attacks of the battle, especially between 24 August and 6 September when these airfields and later aircraft factories became the Luftwaffe's prime targets. Debden, a 'Scheme C' fighter station which opened in April 1937, is also noted for the largely intact preservation of its flying field and defensive perimeter, the most complete of the fighter landscapes completed before and associated with the Battle of Britain after Kenley in Surrey.

This is the most complete example of a sector operations block associated with the critical stage in summer 1940 of the Battle of Britain to have survived from 11 Group, which then took the brunt of the Luftwaffe assault. In contrast to the hipped-roofed single-storey operations blocks of the 1920s expansion of the Royal Air Force (examples at Bicester, Northolt and Duxford—the last two associated with the Battle of Britain), the new designs of 1937, of which this is an example, were protected against incendiaries and bomb blast with a surrounding concrete wall and earth bank. Sector controllers working from these buildings retained executive authority over the aircraft they despatched until they returned to base. The sector controlled from Debden covered the hotly-contested Thames Estuary approach to London.

The operational infrastructure was put in place by Sir Hugh Dowding—in command of Fighter Command during the Battle of Britain—from March 1936, building on his earlier position on the Air Council as Member for Research and Development. Although historians have drawn attention to the production of obsolete aircraft (notoriously exemplified by the Fairey Battle) in order to achieve crude parity with Luftwaffe figures, the early development and sophistication of German radar technology and the speed and manoeuvrability of the new generation of monoplane fighters designed by Camm, Mitchell and Messerschmitt, there is a broad consensus of opinion that it was the infrastructure put in place by Dowding that provided the key to the incisive and economic marshalling of fighter squadrons which guaranteed Fighter Command's survival in the Battle of Britain of 1940.

The system saw Chain Home radar stations (the first five of which became operational in 1938, following development work at Bawdsey) and Observer Corps posts linked by telephone and teleprinter to the Filter Room at Fighter Command Headquarters at Bentley Priory, where plots were checked with those of adjacent stations before decisions concerning deployment and attack could be made. Operations rooms controlled the Groups into which Dowding had subdivided the country. Air Vice Marshall Keith Park commanded the deployment of squadrons within 11 Group, based at Uxbridge. Finally, within each Group, were those operations rooms on the principal sector airfields which controlled the fighter squadrons.

In his detailed description of the 11 Group operations bunker at Uxbridge, Churchill wrote: 'All the ascendancy of the Hurricanes and Spitfires would have been fruitless but for this system of underground control centres and telegraph cables, which had been devised and built before the war under Dowding's advice and impulse'. It could be said that 'Dowding controlled the battle from day to day, Park controlled it from hour to hour, and the 11 Group sector controllers from minute to minute'.

This building is of great importance in relation to the command and control system that guaranteed the survival of the Royal Air Force in one of the key events of the Second World War. It is a remarkably intact example of a distinctive late 1930s design, with many internal fittings including the original air filtration system and the central plotting room. As a consequence of their historical importance, surviving examples of sector operations rooms within 11 Group at Debden and Northolt have been recommended for statutory protection, as well as the all-important Uxbridge bunker and two sector operations blocks on key stations in 12 and 13 Group to the north at Catterick and Duxford.