Heavy Anti-aircraft gunsite, 380m east of Northwick Farm


Heritage Category: Scheduled Monument

List Entry Number: 1019107

Date first listed: 07-Jul-2000


Ordnance survey map of Heavy Anti-aircraft gunsite, 380m east of Northwick Farm
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The building or site itself may lie within the boundary of more than one authority.

County: Essex

District: Castle Point (District Authority)

Parish: Canvey Island

National Grid Reference: TQ 76040 84039, TQ 76131 84011, TQ 76208 84096


Legacy Record - This information may be included in the List Entry Details.

Reasons for Designation

Although of comparatively recent date, 20th century military sites are increasingly seen as historic survivals representing a defining episode in the history of warfare and of the century in general; as such they merit careful record and, in some cases, preservation. One of the more significant developments in the evolution of warfare during this period was the emergence of strategic bombing in World War II, and this significance was reflected by the resources invested in defence, both in terms of personnel and the sites on which they served. During the war, the number of people in Anti-aircraft Command reached a peak of 274,900 men, additional to the women soldiers of the ATS who served on gunsites from summer 1941, and the Home Guard who manned many sites later in the war. A national survey of England's Anti-aircraft provision, based on archive sources, has produced a detailed record of how many sites there were, where they were and what they looked like. It is also now known from a survey of aerial photographs how many of these survive. Anti-aircraft gunsites divide into three main types: those for heavy guns (HAA), light guns (LAA) and batteries for firing primitive unguided rockets (so called ZAA sites). In addition to gunsites, decoy targets were employed to deceive enemy bombers, while fighter command played a complementary and significant role. Following the end of World War II, 192 HAA sites were selected for post-war use as the Nucleus Force, which was finally closed in 1955. The HAA sites contained big guns with the function of engaging high flying strategic bombers, hence their location around the south and east coasts, and close to large cities and industrial and military targets. Of all the gunsites, these were the most substantially built. There were three main types: those for static guns (mostly 4.5 and 3.7 inch); those for 3.7 inch mobile guns; and sites accommodating 5.25 inch weapons. These were all distinct in fabric, though they could all occupy the same position at different dates, or simultaneously by accretion. As well as the four or eight gun emplacements, with their holdfast mountings for the guns, components will generally include operational buildings such as a command post, radar structures including the radar platform, on-site magazines for storing reserve ammunition, gun stores and generating huts, usually one of the standard Nissen hut designs. Domestic sites were also a feature of HAA gunsites, with huts, ablutions blocks, offices, stores and amenities drawn from a common pool of approved structures. Sites were often also provided with structures for their close defence; pillboxes are the most common survivals, though earthwork emplacements were also present. The layout of HAA gunsites was distinctive, but changed over time, for example to accommodate the introduction of radar from December 1940, women soldiers from summer 1941, and eight gun layouts from late 1942. Nearly 1,000 gunsites were built during World War II, and less than 200 of these have some remains surviving. However, at only around 60 sites are these remains thought sufficient to provide an understanding of their original form and function. This includes 30 of the 192 examples which continued in use until 1955. Surviving examples are therefore sufficiently rare to suggest that all 60 well preserved examples are of national importance.

The Heavy Anti-aircraft gunsite 380m east of Northwick Farm is one of the most complete examples in the country. It retains not only the gun emplacements, associated magazine and command post, but also an exceptional collection of ancillary buildings, including some (the pump house and sewage unit) which rarely survive. Considered together with all other variations of Heavy Anti- aircraft gunsite design, TN8 is one of only nine sites to survive (in any form) from an original wartime deployment of about 40 HAA positions across Essex, a pattern designed to combat German bombers on route to London, the Thames estuary and other military targets in the south east of England. In addition, this gunsite is one of the few remaining examples of the `March 1938 pattern' and provides a valuable insight into the development of anti-aircraft measures in the region. It is a significant, visible reminder of the nature of home defence during World War II.


Legacy Record - This information may be included in the List Entry Details.


The World War II Heavy Anti-aircraft gunsite, documented in wartime records as `TN8 (Thames North) Northwick', is located in an area of low-lying pasture within the westernmost peninsula of Canvey Island, bounded to the north by East Haven Creek and to the south by Holehaven Creek. The monument lies in three areas of protection. The first includes the gun emplacements, the command post, the on-site magazine, gun store and the associated section of the military service road. The second area includes the sewage disposal unit which was related to the battery accommodation and is situated some 150m to the east of the gun emplacements. The third area includes the pump house, which stands 150m to the south of the disposal unit and served the facility.

TN8 was designed for the operation of four heavy Anti-aircraft guns, each mounted within an octagonal, shoulder-high concrete emplacement. Three of these enclosures still stand and the foundations of the fourth are thought to survive buried beneath a slight mound. The emplacements are constructed to a recognised design, known as the `March 1938 pattern', arranged in an arc with the apex facing east towards the usual direction of incoming German aircraft. The three standing emplacements each contain six internal recesses built into the internal faces of the surrounding walls. The remaining sides of each octagon were originally fitted with steel gates which could be opened to allow the movement of guns. The on-site magazine bunker, a bomb-proof rectangular building, lies between the two northernmost gun emplacements. A second unroofed rectangular structure, the gunsite command post, occupies the central position within the arc of gun emplacements, accompanied by the generator building which housed the power supply for the guns and locational equipment. The gun store, a concrete garage-like structure, lies some 50m south of the emplacements, to the east of the service road and north of the accommodation huts for the garrison. Eleven of these brick built huts remain in use as light industrial premises. The huts and the related part of the service road are not, therefore, included in the scheduling.

The pump house, a small brick built structure, lies some 10m to the east of the barracks. This served the camp's sewage disposal unit, which consisted of a separation tank and a cluster of small ancillary buildings lying alongside a drainage channel some 130m to the north east.

War Office documents on gunsite TN8 indicate that the battery was operational by 1940 and mounted three 4.5 inch guns in June of that year, manned by 171 battalion of the 6th Anti-aircraft Division.

Container units and other modern items overlying the gunsite are excluded from the scheduling, although wartime structures and surfaces beneath items are included.

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.

Legacy System number: 32433

Legacy System: RSM


Books and journals
Dobinson, C S, Twentieth Century Fortifications in England: Volume 1, (1996), 469-72
Dobinson, C S, Twentieth Century Fortifications in England: Volume 1.4, (1996), 469-72
Nash, F, World War Two Heavy Anti-Aircraft Gun Sites in Essex, (1998)
9 colour prints, Carter, PJ, Frames 27 to 35, (1999)
9 colour prints, Carter, PJ, Frames 27 to 35, (1999)
Aerofilms, 90-234 Run 84 7053, (1990)
Black and white vertical, Aerofilms, 90-234 Run 84 7053, (1990)
Colour prints, Carter, PJ, Frames 27 to 35, (1999)
HQ 6th AA Division Location List, (1940)
HQ 6th AA Division Location List, (1940)
HQ, 6th Div., Location List HQ, 6th Div., (1940)
RAF, Run 38-020, (1960)
Tyler, S, MPP Film 7, (1999)
Vertical black and white, Aerofilms, Aerofilms 90-234 Run 84 7053, (1990)
Vertical black and white, RAF, Run 38-020, (1960)

End of official listing