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A World War II Chain Home Radar station at Dunkirk, 200m north east of Christ Church

A Scheduled Monument in Dunkirk, Kent

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Coordinates

Latitude: 51.2957 / 51°17'44"N

Longitude: 0.9779 / 0°58'40"E

OS Eastings: 607709.877654

OS Northings: 159381.970559

OS Grid: TR077593

Mapcode National: GBR SWF.N2W

Mapcode Global: VHKJX.WPVM

Entry Name: A World War II Chain Home Radar station at Dunkirk, 200m north east of Christ Church

Scheduled Date: 29 January 2003

Source: Historic England

Source ID: 1020388

English Heritage Legacy ID: 34310

County: Kent

Civil Parish: Dunkirk

Built-Up Area: Dunkirk

Traditional County: Kent

Lieutenancy Area (Ceremonial County): Kent

Details

The monument, which falls into six separate areas of protection, includes a
World War II Chain Home Radar station, situated on high, level ground
approximately 6km west of Canterbury. The main compound of the radar station
is bound on its eastern side by Courtney Road and by the Canterbury to London
road to the south.
Successful experiments during the early 1930s into the use of radio waves as a
method of detecting and locating aircraft, led to the implementation of a
chain of Radio Direction Finding (RDF) stations, later known as RADAR, along
the eastern, and ultimately the western coast of Britain. Dunkirk was one of
the first five operational stations which made up the so-called Estuary Chain
Home layout, established in 1936-38 to provide long range early warning of
high flying enemy aircraft for the Thames Estuary and the south eastern
approaches to London. Initially established as a single tower transmitter-only
site in 1936, Dunkirk was upgraded to a transmitter/receiver station the
following year, with the subsequent addition of eight further towers.
The station played a vital role in Britain's domestic air defence throughout
the war, particularly during episodes such as the Battle of Britain in 1940
and the V-weapon attacks of 1944-45. After the war, Dunkirk became one of 32
stations in the first phase of the programme to restore Britain's air defence
control and reporting system during the early Cold War period, known as
`Operation Rotor'. However, during the 1950s British radar entered a new era,
to meet the threat of guided weapons, and by 1958 the station had closed and
its equipment was sold. All but one of the radar towers were demolished the
following year. The surviving transmitter tower was retained by the Ministry
of Defence, and remains in use for communication purposes. It is a rare
surviving example of a Chain Home tower. The transmitter tower is a
Listed Building Grade II, and is not included in the scheduling.
The station's north-south aligned, roughly rectangular compound, occupies an
area some 500m by 600m on the north western side of Dunkirk village. It was
enclosed by 3m high spiked steel railings, parts of which survive on the
southern and eastern edge of the site. Sections of an outer, flanking ditch
are also visible to the north and east. The internal layout of the station,
which is largely unaffected by later development, followed the standard
compact design common to all East Coast stations. Its technical equipment was
concentrated in two large rectangular buildings, known as the Receiver and
Transmitter Blocks. For blast protection these brick and concrete structures
were externally embanked, with entrances traversed and a 1.7m thick layer of
shingle enclosed within the roof. The shingle has been removed from the
Transmitter Block, although both buildings retain their other forms of blast
protection, as well as much of their internal layout.
The Transmitter Block, located in the south eastern area of the compound,
about 200m north west of the village crossroads, housed the transmitter
equipment, which delivered pulses of high frequency energy from antenna
erected on four 350ft (107m) high self-supporting towers arranged in a line in
front of the building. These were known as Group III transmitter towers, built
by JL Eve Construction Company to a slightly different specification to Chain
Home towers elsewhere. The echo reflected by an aircraft within the
`illuminated' area was picked up by the antenna of the adjacent receiver
system installed on four 240ft (73m) high wooden towers, arranged around the
central Receiver Block, located about 600m north west of the crossroads. From
the information received by the equipment within the Receiver Block, it was
possible for the crew to identify the position of the aircraft, the number of
aircraft within a formation and also to distinguish between allied and enemy
planes, through the use of aircraft mounted apparatus known as `Identification
Friend or Foe' or IFF. Information was passed to the Fighter Group
Headquarters where the enemy aircraft locations were plotted and the pursuit
planes dispatched to intercept them.
Other components of the technical site included a large square structure, also
banked and traversed for blast protection, located between the transmitter and
receiver systems, and this housed the standby generator set. The station was
also provided with reserve transmitter and receiver equipment housed in two
underground buildings, called the Buried Reserves, located in the northern
sector of the compound. Access into the chambers is now prevented by flooding,
and other obstacles, although the sliding entrance hatches, emergency exits
and ventilation ducts can be seen at ground level, together with the concrete
bases for the two 105ft (32m) wooden towers, which were to be left un-erected
and camouflaged until needed.
The importance of radar stations, in providing long range early warning, was
fully recognised during World War II and a high priority was given to their
defence. By 1939 Dunkirk radar station, which fell within Fighter Command's
strategically important 11 Group (that part of Fighter Command covering the
south east of England), was identified by the war office as one of five sites
in England most vulnerable to attack and was allocated the designation
`Vulnerable Point (VP) 126'. In common with other VPs, Dunkirk subsequently
became a strongly fortified position. From as early as September 1939 the
site's anti-aircraft provision included three 40mm Bofors and eight Lewis
guns. Fears of German paratroop raids led to the construction of additional
perimeter defences, including four infantry pillboxes, which survive on the
southern and eastern sides of the compound, and Lewis guns for ground defence.
By July 1940 the number of Lewis guns had been temporarily increased to 18.
The defences were further strengthened by the addition of a tower-mounted
Bofors gun and a quad-mounted Vickers machine gun, both of which were in
place by the end of January 1942. The Bofors tower formed part of the western
perimeter defences of the station and survives in Clay Pits Wood. This is a
rare surviving example of a light anti-aircraft gun tower, and is a
Listed Building Grade II. Other surviving emplacements include two octagonal
gunpits, one situated close to the Buried Reserve and the other adjacent to a
pillbox on the eastern perimeter of the site, now located within the garden of
a modern house. Two rectangular, internally partitioned and externally mounted
brick built positions also survive on the northern edge of the compound, one
of which retains the steel mounting pivot for the gun.
Other structures located within the main compound include the brick remains of
the sewage collection tanks to the north east of the Receiver Block; a
concrete lined fire fighting pond east of the receiver system and the concrete
foundations of camp buildings along the access track from Courtenay Road. The
married quarters for the site wardens also survive at the former entrance on
Courtenay Road. These are occupied as private residences and are therefore
not included in the area of protection.
Some outlying structures, associated with the operation of the station, also
survive outside the perimeter fence. These include a semi-sunken air raid
shelter, known as a Stanton shelter, located approximately 90m north of the
compound, together with a small brick structure, which is thought to be a
junction box associated with the station's communication system or electrical
supply. Approximately 220m east of the north eastern corner of the compound,
on the western edge of Bossenden Wood, is a brick built ammunition store,
measuring approximately 10 sq m, protected beneath an earthen mound. This
appears to have served the station's northern and eastern defences. A
rectangular surface building of concrete block construction, with a baffle
entrance and a heavy steel door, is located on the eastern side of Courtenay
Road about 500m north east of the compound and has been interpreted as either
a weapon store or surface air raid shelter. A further structure survives on
the eastern side of Courtenay Road, in the garden of Firtree Cottages,
approximately 950m north east of the radar station. It consists of two
parallel, north-south aligned, substantial brick walls, with gently sloping
terminals to the north and steeply battered to the south. Its walls are
embanked to the east, and its concrete roof is recessed and filled with earth.
The structure, which was originally open at each end and now enclosed for use
as a stable and garden store, is thought to have been either an emergency
shelter for fire fighting vehicles or a camouflaged shelter for a mobile
anti-aircraft gun. Further, as yet unidentified buildings associated with the
use of the former radar station may survive beyond the area of protection.
In addition to the modern stable constructed between the concrete bases of the
first RDF tower, the following items are excluded from the scheduling: all
later surfaces and structures, fences, gates, and goal posts; materials
used to seal the doors and/or windows of some of the surviving buildings, and
all modern materials and equipment stored within and around the buildings.
However, the ground beneath these features and/or the structures to which they
are attached, are included in the scheduling.

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

Source: Historic England

Reasons for Scheduling

The introduction of the aircraft as an offensive weapon is significant in the
history of 20th century warfare, while the bomber's ability 'always to get
through' provided the rationale for strategic air defence systems adopted by
Britain from the early 1920s. These systems initially involved early warning,
based on the visual spotting and tracking of aircraft, but developed through
acoustic detection devices to radar.
The principles behind radar were widely recognised by the 1930s, but British
technicians were the first to mould the basic science - that an
electromagnetic pulse reflected from an object betrays that object's position
to a receiver - into a practical means of air defence. Following experimental
work at Orfordness and Bawdsey in Suffolk, radar developed through the initial
Home Chain, to Chain Home Low (CHL) stations, which filled gaps in low-looking
cover left by the original technology. Both were designed for raid reporting,
passing information to a central operations room which in turn directed
fighters to intercept enemy aircraft. This system was vital in the Battle of
Britain. Radar was then adapted during the Blitz of 1940-1 to incorporate a
system of Ground Controlled Interception (GCI) by which night fighters were
controlled directly rather than via a central operations room. A further
addition in 1941 was Coast Defence/Chain Home Low (CD/CHL), a low-cover
coastal radar designed to detect surface shipping. Originally manned by the
Army, these coastal sites were ultimately handed over to the RAF, thereby
unifying the low cover chain. At this time many stations were converted to new
and more powerful equipment, known as Chain Home Extra Low (CHEL). Finally, in
1943 Fighter Direction radar was developed to aid Fighter Command in their
offensive sweeps over occupied Europe. Many radar stations were reused during
the Cold War period for Rotor, a later development of wartime radar.
A national survey of radar stations has identified some 242 sites at 200
separate locations - some quite extensive - used for by radar reporting and
control functions during World War II. Forty-seven of these are Chain Home
sites, about half of which survive in some form, seventeen of which are
complete or near complete. These were large sites with some substantial
components, the design and specifications of which evolved according to
technological developments. There were also regional variations, such as in
building design between east and west coast sites. Characteristic features
include transmitter and receiver towers and blocks, buried reserves providing
an independent system in case of attack, defence structures, a guard hut and
associated domestic camps.
Chain Home sites with significant surviving remains representing the site's
primary function are considered to be of national importance. Chain Home
towers are rare nationally and all surviving examples are of national
importance.

The World War II Chain Home Radar station at Dunkirk, 200m north east of
Christ Church is particularly important in terms of the development and early
implementation of radar, representing its first use beyond the experimental
phase. The station survives well and is one of only seven Chain Home sites
nationally which is virtually complete, with its ground structures and layout
still visible and its interior untouched by modern development. It therefore
provides an understanding of the original form and function of Chain Home
stations and as such, it is an important historic complex, serving as a
physical record of similar stations which have been demolished elsewhere.
Historically, the importance of the site is further enhanced by the
significant part it played in the defence of Britain against aerial
bombardment throughout World War II, and its continued significance during the
early Cold War period.
Surviving Chain Home transmitter towers are extremely rare nationally and
Dunkirk is one of only five sites to retain any of their original towers. The
survival of the tower greatly amplifies the significance of the site.
Furthermore, it is a prominent feature in the landscape which has become a
familiar local landmark and a fitting tribute to those who served in the
defence of Britain during the principal conflict of the 20th century. The
transmitter tower is protected as a Listed Building Grade II.

Source: Historic England

Sources

Books and journals
Anderton, M, World War Two Radar Stations - Survey Report, (2000)
Dobinson, C S, Twentieth Century Fortifications in England: Acoustics and Radar, (2000)
Eve, , Brown, , Chain Home AMES Type 1: East Coast Tx Tower Group III, (1930)
Lowry, B (ed), Twentieth Century defences in Britain. An introductory guide, (1995)
Other
Air Ministry, AVIA 15/792: Chain Home Stations (Secret), (1942)
Ministry of Defence, MoD Technical Bulletin, Masts and towers: standard nomenclature guidance..., (2000)
RAF, 106g/uk/1449;4033, (1946)

Source: Historic England

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