In 1938 Northumberland Bottom was identified as a suitable site for a four-gun 4.5-inch heavy anti-aircraft battery. The four guns were placed in concrete placements arranged in a half circle facing south-east. Barracks accommodation was provided to the north-west. By 1942 a radar station was added bringing the total manning to 312. This more than doubled, by 1943, to 747 including female personnel as well. The site does not seem to have been designated as an Operation Diver, anti V1 rocket, battery so it is possible that the guns may have been withdrawn and re-deployed elsewhere in 1944. After the war the site was mothballed and apparently used as a civil defence training camp until the 1960’s. A Royal Observer Corp observation post was established in the vicinity, probably as a nuclear fall-out monitoring post, but its location has not been established.

A building survey of the camp was undertaken in 1998. Along with the barrack buildings and the heavy anti-aircraft gun emplacements other structures were also noted. These included: a 40mm Bofors gun emplacement (it is unclear when this was built), a guard house and guard dog kennels, Kitchen and canteen, workshop, cinema lecture theatre, air-raid shelter and sanitation works. No evidence of the gun magazines or for defensive trenches has been found. The site seems to have been completely destroyed by the Channel Tunnel Rail Link and associated works in 1999.(1-3)

Description from record TQ 67 SW 1346:
Second World War heavy anti-aircraft battery on the rise above Northumberland Bottom at Gravesend, designated S17 and within the area of 6 AA Division.. It was built in 1938 and although intended for 4.5-in. guns was mounted with 4 x 3.7-in. guns in individual concrete octagonal emplacements. To these was centred a rectangular concrete command post with a flat roof, with surface elements for a spotting telescope, height finder and other instruments. Within were rooms for the command staff and for telephones. The domestic site was in huts about 50 to the west. After 1940 two further guns were provided in square emplacements with bevelled corners. There were two rectangular magazines reached by covered ways. There was a radar installation for gun direction. The battery saw action but although decommissioned at the end of the war in Europe in 1945 was retained as a contingency under the Igloo Scheme for post war use. Its final decommissioning was in 1956. Afterwards it became part of a riding stable and the site was cleared for the Channel Tunnel Rail Link in 2000.
Owner : Unknown
Publicly accessible : No
How accessed for survey : Site destroyed
Tourism Potential : None
Condition : Destroyed
Date of visit : 27/01/07

The site is visible on aerial photographs of 1961 and shows some post-war changes, perhaps relating to Igloo works. Additionally, the area of the gun emplacements lies to the south of the CTRL and below ground features may survive in places.

Council for British archaeology, 01/01/96, Twentieth century Fortifications in England, Vol. I.1 Anti-aircraft artillery (Bibliographic reference). SKE14026.

<1> Museum of London Archaeology Service, 1999, Northumberland Bottom Army Camp: Standing Building Survey Interim Report (Unpublished document). SKE12761.

<2> Museum of London Archaeology Service, 2000, Channel Tunnel Rail Link Contracts 330 & 350 Watching Brief ARC 330 98 Interim Report (Volume 1 of 2) (Unpublished document). SKE12773.

<3> Museum of London Archaeology Service, 2000, Channel Tunnel Rail Link Contracts 330 & 350 Watching Brief ARC 330 98 Interim Report (Volume 2 of 2)
Channel Tunnel Rail Link Contracts 330 & 350 Watching Brief ARC 330 98 Interim Report (Volume 2of 2) (Unpublished document). SKE12774.