A London mobilisation centre known as the North Weald Redoubt


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Scheduled Monument
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Ordnance survey map of A London mobilisation centre known as the North Weald Redoubt
© Crown Copyright and database right 2019. All rights reserved. Ordnance Survey Licence number 100024900.
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The building or site itself may lie within the boundary of more than one authority.

Epping Forest (District Authority)
Epping Forest (District Authority)
North Weald Bassett
National Grid Reference:
TL 50562 03972

Reasons for Designation

The 15 London mobilisation centres, constructed during the 1890s, formed part of a comprehensive military scheme known as the London Defence Positions, drawn up in 1888 to protect the capital in the event of enemy invasion. The scheme was a response to the rapid progress made in warship production by France and Russia during the early 1880s, which had led to official doubts about the Royal Navy's defence capability. Essentially a contingency plan, it provided for the establishment of a 72 mile long, entrenched stop-line divided into ten tactical sectors and supported by artillery batteries and redoubts. The planned stop-line ran from the southern edge of the Surrey and Kent Downs, up the western side of the Darenth Valley to the Thames, and then north westwards through Essex from Tilbury Fort to Epping. Although the stop-line and main defence positions were not to be established until an invasion was imminent, it was thought prudent to build a series of mobilisation centres, 13 on new sites, along the projected course, either for artillery deployment or where troops could assemble and collect tools and supplies. By 1905, official confidence in the Royal Navy had been restored, and the now obsolete mobilisation centres were abandoned and gradually sold off. No two mobilisation centres are exactly alike, and a broad distinction can be drawn between the four centres purpose built for artillery deployment, and eight which functioned as infantry positions. However, in general terms there are close similarities: each, for example, was typically enclosed by a rampart, ditch and spiked fence, containing a partly earth-sheltered, reinforced concrete and brick built magazine and stores. Beyond the main compound were associated buildings of a standard type, including a brick caretakers lodge and a large, barn-like tool store. Most mobilisation centres have been the subject of subsequent alteration and/or reuse. As a short-lived and rare monument type, all mobilisation centres with surviving remains sufficient to give a clear impression of their original form and function are considered to be nationally important.

The North Weald London Mobilisation centre, officially known as The North Weald Redoubt exhibits a remarkable level of survival, no doubt largely as a result of the sympathetic (or cost-effective) reuse of the site as a radio station after the First World War. Not only do the earthworks and casemates of the main compound remain substantially intact but, unusually for this type of monument, the contemporary caretakers' cottages and external stores also survive with few modifications when compared to the original War Office plans. As with all more recent military installations, the operational use of the centre is poorly recorded; these plans, however, provide clear documentary evidence for the design and intended use of this, the most northerly of the mobilisation centres within the ring of the London Defence Positions. The Allen-Williams turret is a well preserved example of a comparatively rare form of gun emplacement, a small number of which were produced in 1939-40 by a company specialising in pre-fabricated building components. Unusually, it still retains all the principal elements of its dual purpose design, and its use in this location illustrates the renewed military significance of the redoubt as a radio station during World War II.


The monument includes the main compound, caretakers' cottages and external stores of the North Weald London mobilisation centre, a late Victorian and Edwardian military store and mustering station situated on rising ground to the east of North Weald Bassett (within the grounds of the former Ongar Radio Station), and known variously as the Essex or North Weald Redoubt.

The main compound is broadly `D'-shaped in plan. A 15m wide, semi-circular ditch defines the north eastern `front' of the installation and a straight channel, some 180m in length, completes the rear of the circuit to the south west. The rear channel, known as `the gorge', contains a sunken roadway and a row of reinforced concrete casemates which extend right along the northern side. These, according to the War Office specifications of 1893, could be used to accommodate 72 men. The majority of the chambers still retain half-inch steel doors facing into the gorge, as well as wooden doors in the connecting corridors and other internal fittings. The gorge is approached by two vehicle ramps, one at the eastern end, the other descending the outer scarp from the bridge which carries the principal access road across the gorge and onto the reinforced roof of the casemates. The bridge, flanked by high walls and massive cylindrical gate piers, overlies a caponier - a strongly-built passageway linked to the casemates and pierced by loopholes to allow enfilade rifle fire along the length of the gorge.

The approach road continues along the length of the casemates' roof, joining two internal routes which lead northwards into the inner or `front' section of the installation. This section includes a sunken semi-circular marshalling yard, reached by shallow ramps and screened from the south by a massive earthen blast wall. The northern side of the yard contains a curved row of concrete casemates which carries the loop of the internal road across its roof and is recessed behind a strong earthen rampart which matches the curvature of the outer ditch.

The front casemates are well documented and the purpose of every chamber is known. The row is divided into three main sections, one in the middle of the curve and one at either end; the sections are separated by double fronted rooms termed `gun casemates' (probably used for storing artillery pieces) flanked by single chambers used as general artillery stores. Each of the three main sections contains a `shifting lobby' (where protective and non-sparking clothes were kept for magazine personnel), two cartridge stores joined by a rear passage, and a separate shell store linked by an expense hatch. The shell stores in the outer two sections also contained hoists leading to roof apertures. The central section has a separate hoist chamber. The chambers which were not used to store munitions are furnished with ventilation ports in the ceiling and some also have windows facing into the yard. To minimise the risk of explosion, however, the cartridge and shell stores were not ventilated and the only light was provided by lamps set behind reinforced plate glass windows and only accessible from the outer faces of the dividing walls. Although the steel doors and shell hoists have been removed from the front casemates, some of the original fittings survive. These include wooden internal doors and expense hatch covers, lamp recess casements and some of the original notices labelling various components of the magazines.

Although not essentially designed as a fort, the mobilisation centre did have a defensive aspect and was certainly considered as a potential redoubt from which to maintain resistance if adjacent sections of the defence line were overrun. The earthen bank to the north of the front casemate, as well as serving as a blast wall around the magazine, was also designed with the potential for mounting a battery of six guns behind a series of projecting bastions. Although the main guns were never installed, the casemates were fitted with two forward passages, giving access to hollows in front of the bastions which may have been intended as weapon pits. In addition to this, the entire complex was surrounded by a wire fence set back from the ditch, and the ditch itself contained tall spiked railings known as a dacoit fence. Both these features have since been removed.

The North Weald Redoubt was not intended to be permanently garrisoned, but provision was made for caretakers. Two uninhabited single-storey cottages, brick-built with slate roofs, stand within the line of the original perimeter fence, immediately to the south of the bridge. Both conform to standard military designs of the period - that to the east of the access road dating from 1890 (during the first stages of the centre's construction) and that to the west added in 1893. Immediately to the east of the earlier cottage stands a small square building of similar construction. This, although later used as a boiler room, has been identified with a blanket store proposed in 1904. To the east of this building are two rectangular halls, set in line, also brick-built with rivetted iron trusses supporting a slate roof. These are additional shell and cartridge stores documented on War Office plans dating from 1904. They remain essentially discrete structures, largely unaltered and intact despite their amalgamation with a later radio station workshop on the south side (which is not included in the scheduling). Buried beneath ground level to the east of the eastern store is a large water tank added in 1904 and linked to an earlier concrete cistern set in the southern face of the gorge. A similar cistern, designed to serve the needs of the front casemates, is located on the southern side of the inner yard.

Construction of the North Weald Redoubt began shortly after the land was purchased in 1889 and was largely completed by 1904. It was retained as a military base in the decade leading up to 1914, and it is then thought to have served as an arsenal for the duration of the Great War. In 1919 the site was sold at auction to the Marconi Wireless Telegraph Company, who established a radio station on the surrounding hillside (the last original radio mast from this period was taken down in 1982) and used the redoubt for storage. The Imperial and International Communication Company took over the site in 1929 and continued operations under the new name of Cable and Wireless after 1934.

The radio station came under direct government control during World War II and this use, plus the site's proximity to the Southern Fighter Command base at North Weald airfield, may explain the presence of an unusual form of World War II gun emplacement, known as the `Allen-Williams' turret, situated on the south eastern terminal of the rampart above the eastern approach to the gorge. It consists of a rotating steel dome, 1.5m in diameter, set over a concrete lined pit with an entrance passage to the west. The dome contains space for two men, one to rotate the upper section, the other to operate the armament (since removed) which could include the Bren or Lewis machine gun or the Boys anti-tank rifle. The machine guns could be mounted through the square aperture in the side of the turret or the circular opening above. It could thus be used against both ground and aerial attack. After the war in 1950, the radio station came under the control of the Post Office and the redoubt was used and maintained by the GPO (and latterly British Telecom) until the site was decommissioned in the early 1990s.

A number of features within the area of the monument are excluded from the scheduling; these are the timber-built rigging workshop overlying the eastern end of the gorge casemates, the brick-built workshop (most recently used as an engine generator test centre) attached to the southern side of the 1904 cartridge and shell stores and the comparatively modern annexes attached to the eastern end of the latter building, the comparatively modern garage building within the inner courtyard, all modern oil tanks, their brick supports and all modern vehicle inspection ramps, all modern fences, fenceposts and gates surrounding the perimeter of the monument; however the ground beneath these features is included in the scheduling, together with the structures and surfaces related to the military use of the site, to which some of these features are attached.

MAP EXTRACT The site of the monument is shown on the attached map extract.


The contents of this record have been generated from a legacy data system.

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Books and journals
Beane, A, A History of North Weald Bassett, (1884), 125,140
Sprack, P, Allen-Williams Steel Turret: Bembridge Fort, Isle of Wight., (1989)
Kent, P, 'Fortress' in East Anglian Fortifications in the Twentieth Century, , Vol. 3, (1989), 54
Smith, V, 'London Archaeologist' in The London Mobilisation Centres, , Vol. 2,10, (1975), 244-48
AM107 site report, Chant, K, Essex Redoubt at the Ongar Radio Station, (1987)
copies at Imperial War, Duxford, War Office, North Weald Redoubt (WO 78 2404), (1892)
copies at Imperial War, Duxford, War Office, North Weald Redoubt (WO 78 2606), (1893)
copy at Imperial War Museum, Duxford, War Office, North Weald Redoubt Record Plan No.5, (1904)
discussions with Def of Brit officer, Samson, M, North Weald Redoubt, (1998)
info from Defence of Britain office., Samson, M, North Weald Airfield and the Battle of Britain, (1998)
supported by Defence of Britain Proj, Beard, P, North Weald Redoubt - draft discussion document, (1995)


This monument is scheduled under the Ancient Monuments and Archaeological Areas Act 1979 as amended as it appears to the Secretary of State to be of national importance. This entry is a copy, the original is held by the Department for Digital, Culture, Media and Sport.

End of official listing

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