Ancient Monuments

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Royal Observer Corps underground monitoring post and World War II visual spotting post, 200m north of Southfield House

A Scheduled Monument in Skipsea, East Riding of Yorkshire

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Latitude: 53.9758 / 53°58'32"N

Longitude: -0.209 / 0°12'32"W

OS Eastings: 517561.649377

OS Northings: 454788.59448

OS Grid: TA175547

Mapcode National: GBR VQZG.KJ

Mapcode Global: WHHFS.RBNF

Entry Name: Royal Observer Corps underground monitoring post and World War II visual spotting post, 200m north of Southfield House

Scheduled Date: 15 April 2004

Source: Historic England

Source ID: 1021192

English Heritage Legacy ID: 35490

County: East Riding of Yorkshire

Civil Parish: Skipsea

Traditional County: Yorkshire

Lieutenancy Area (Ceremonial County): East Riding of Yorkshire

Church of England Parish: Skipsea All Saints

Church of England Diocese: York


The monument includes a Royal Observer Corps(ROC) underground monitoring
post and adjacent World War II visual spotting post standing within a
fenced enclosure. It is located on the east coast of Yorkshire to the
south east of Skipsea.

There has been an ROC presence at Skipsea since at least the early 1940s
when a visual observation post was in place to monitor aircraft during the
early stages World War II. The post closed down in 1945 but was reopened
in the early 1950s and continued to be used by the ROC for visual spotting
of aircraft during the Cold War until 1963. In 1959 an underground post
was opened for the ROC's new role of monitoring nuclear attack and fall
out. It was a master post supervising a cluster of three other posts and
reporting to the 20 Group headquarters in York. The monitoring post
continued in use until 1991 when it closed as part of the winding down of
ROC operations nationwide.

The underground monitoring post follows the standard Cold War design and
consists of a rectangular-shaped reinforced concrete underground bunker
concealed beneath a mound of earth on an east to west alignment.
Protruding from the top of the mound are an access hatch at the eastern
end, an air vent at the western end and two metal monitoring probes in

The access hatch has a counterweighted metal lid which opens to reveal a
4.6m deep shaft containing a single metal ladder. At the bottom of the
shaft there is a small chamber containing a chemical toilet and a door
leading to the main chamber. This measures 5.8m by 2.6m and originally
housed the monitoring equipment and rudimentary domestic facilities for a
crew of three. At Skipsea a number of the original fittings survive
including the intake apparatus for the monitoring equipment as well as a
desk, cupboard, tool rack and chemical toilet. ROC bunkers could be very
cold and many posts installed their own insulation. At Skipsea this
included covering the floor with conveyor belt rubber and lining the walls
with polystyrene tiles. In total the bunker and protective mound measures
14m by 8m.

The visual spotting post lies to the east of the mound. This follows a
typical 1940s design and includes a brick built structure measuring 3.5m
by 4m with a concrete roof. The door on the west end leads to a narrow
room extending the length of the structure which acted as a store and
shelter: the original stove for providing warmth and cooking still
survives. To the south of this and occupying the bulk of the structure is
the plotting room. There is a large circular opening in the roof of this
room which allowed for the aircraft plotting instrument to have an
unobstructed view of the skies. The floor of the room has been heavily
undermined by rabbits although the lower part of the wooden post which
supported the plotting table still survives. Attached to the western side
of the structure there is a corrugated tin latrine and store.

The original enclosure surrounding the post still survives. It is has a
simple post and rail fence with a picket gate at the western side. In
total it measures 26m east to west by 17m north to south.

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

Source: Historic England

Reasons for Scheduling

The archaeological remains of the Cold War (1946-1989) are the physical
manifestation of the global divide between capitalism and communism that
shaped the history of the late 20th century. This was a period when the
two superpowers, and their allies, developed massive nuclear arsenals and
civil defence structures to counter the threat of nuclear war. The
construction of Royal Observer Corps (ROC) Underground Monitoring Posts
from the late 1950s reflected the changed reality of the Cold War brought
about by the deployment of new technologies including the hydrogen bomb,
which threatened massive destruction and radioactive contamination.
The early stages of the Cold War saw the ROC involved in the visual
detection and identification of aircraft, a role they had previously
carried out in World War II. The corps, in existence since 1925, had
established a network of observation posts and a national reporting system
which was reinstated in 1948 to meet the new threat of the Cold War. These
posts used existing World War II posts or a new structure introduced in
1952 known as an Orlit Post. This was a rectangular box formed from
precast concrete panels, either sited on the ground or elevated on
concrete legs or in a number of cases on pillboxes. ROC visual observation
posts were equipped with a Micklethwaite instrument which enabled the
altitude and direction of aircraft to be plotted. This, coupled with an
observer's visual identification of the make of an aircraft, meant
accurate information could be reported. By the late 1950s the development
of faster jet aircraft made the visual reporting of aircraft ineffective
and this role was finally abandoned in 1965 and above ground posts were
In the late 1950s the ROC took on the primary responsibility of monitoring
and reporting the location and impact of nuclear attack. Construction of
the system of Underground Monitoring Posts began in the late 1950s and was
largely complete by 1965. Although some new posts continued to be built
into the 1970s, a large number of the early underground posts were
decommissioned in 1968. The last posts were abandoned when the Royal
Observer Corps was stood down in 1991 following the end of the Cold War.
Individual posts were formed into clusters of three or four sites
providing co-ordinated raid reports via a master post to the group
headquarters. Posts were usually built at the sites of earlier ROC
observation posts and used the existing nationwide reporting system
already established by the ROC. The posts had three main tasks: to confirm
that a nuclear attack had taken place and its location; to estimate its
power; and to monitor the passage of radioactive fallout. The posts were
designed to operate in a post-nuclear attack environment, and to be self
sufficient for an operational life of up to 14 days. All are buried to
provide protection from blast and heat, and to reduce radiation
The visible remains usually include an elongated mound with an entrance
hatch, ventilator and attachments for the monitoring devices protruding
from the surface. Internally the post was divided into two chambers.
One, at the bottom of the access shaft, contained a chemical toilet and
led into the second, a larger monitoring room in which were bunks, a desk,
batteries for power, and a hand operated ventilation system. The
monitoring equipment measured the intensity of an explosion using a simple
pressure device called a bomb power indicator, the location, altitude and
magnitude using an instrument called the ground zero indicator and the
level of radiation fall out using a Geiger counter.
Underground Monitoring Posts were the most numerous structures built in
the United Kingdom during the Cold War. In total around 1518 were built
(1026 in England). However, the number of active posts was nearly halved
in 1968 due to the diminished risk of attack and to reduce defence
Following a survey of Cold War monuments all of the posts have been
located, and those where they survive structurally intact and where
fittings remain are considered to be of national importance. Their
significance will be enhanced where they are associated with earlier, or
contemporary, visual reporting posts, reflecting the changing role of the
ROC during the Cold War.

The remains of the ROC early warning and monitoring posts at Skipsea
survive well and significant remains of their form and operation is
preserved. The early visual spotting post is relatively rare and together
with the underground post provides evidence of the history and development
of early warning systems during the 20th century.

Source: Historic England


Books and journals
Brown, et al, 20th Century Defences in Britain, (2001), 32-33
Thomas, R, (2003)

Source: Historic England

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