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Fosterdown or Pilgrim Fort: a London mobilisation centre

A Scheduled Monument in Caterham Valley, Surrey

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Latitude: 51.2634 / 51°15'48"N

Longitude: -0.0747 / 0°4'29"W

OS Eastings: 534422.087112

OS Northings: 153341.486557

OS Grid: TQ344533

Mapcode National: GBR KK3.RX7

Mapcode Global: VHGS5.NHBV

Entry Name: Fosterdown or Pilgrim Fort: a London mobilisation centre

Scheduled Date: 27 July 1973

Last Amended: 7 June 2000

Source: Historic England

Source ID: 1019288

English Heritage Legacy ID: 32276

County: Surrey

Civil Parish: Caterham Valley

Traditional County: Surrey

Lieutenancy Area (Ceremonial County): Surrey

Church of England Parish: Godstone and Blindley Heath

Church of England Diocese: Southwark


The monument includes the main compound of Fosterdown Fort, also known as
Pilgrim Fort, situated on a southern spur of the North Downs, around 1km south
of Caterham.
The main, south facing compound, is roughly circular in plan and is defined by
a large, earthen rampart. The shallow, surrounding ditch, which is in turn
encircled by a low bank, contained spiked metal railings which completely
enclosed the compound.
Access to the interior is from the gorge to the north or rear of the compound
through a gap in the rampart, which is flanked by low concrete walls which
meet its rear-curving ends.
The entrance is approached by a track from the north, and opens onto an almost
square, north west-south east aligned central parade. Its concrete walls, on
the north eastern and western sides, extend to join the low gorge walls.
The parade is defined on its south western side by a three roomed magazine,
set into the rear of the forward rampart, just below the internal ground
level. To minimise the risk of explosion, the magazine chambers were lit by
lamps, set in recesses behind panes of glass, and accessed from the lamp
passage which surrounds the magazine. The corridor in front of the chambers
was divided into two sections by the addition of a partition wall. The short
passage in front of the cartridge store contained a shifting lobby, just
inside the entrance, where magazine personnel changed into protective and
non-spark producing clothes. A separate entrance for the two shell stores, in
the south eastern portion of the magazine corridor, also provided access to
the lamp passage and two small chambers designed to store lamps and fuses. On
either side of the partition wall, the outer wall of the corridor is pierced
by two issuing hatches, through which ammunition was passed outside for
collection. The magazine retains many of its original features, including two
windows facing into the parade, and wooden shutters in the ceiling of the
shell stores, designed to control the circulation of air through the
ventilation ports.
A four roomed casemate block, set into the rampart just below ground level,
defines the south eastern side of the parade. At each end of the casemates,
steps lead up from the parade onto the top of the rampart, which could
function as a firing parapet, allowing the mobilisation centre some degree of
self-defence in the event of enemy bombardment.
After the London Defence Positions were abandoned, in around 1905, the centre
was finally sold in 1920. It was subsequently used, for much of the 20th
century, as a field study centre for school groups. To meet their needs, the
casemates were converted into washrooms and drying rooms, and two brick
chimney stacks were constructed on the flat roof, above the ventilation
Associated with the main compound are the original, semi-detached pair of
caretakers' cottages and the mobilisation tool store, situated on the eastern
side of the approach road from the north. The cottages, situated around 80m
north of the compound, have been converted into a private residence, and the
mobilisation tool store, which is Grade II Listed, located just outside the
entrance, is undergoing conversion for an alternative use. These buildings are
therefore not included in the scheduling.
A number of features within the area of the monument are excluded from the
scheduling. These are: all modern fences; all modern fixtures and fittings,
including all components of the modern electrical and plumbing systems, as
well as modern materials and equipment stored within the mobilisation centre;
and the wooden sheds, constructed on the north eastern edge of the rampart and
ditch. The ground beneath these items is included in the scheduling, together
with structures and surfaces related to the military use of the site, to which
some of these features are attached.

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

Source: Historic England

Reasons for Scheduling

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.

Despite some alteration and renovation, Fosterdown Fort survives comparatively
well, and will retain evidence relating to the construction and use of
mobilisation centres.

Source: Historic England


Books and journals
Smith, V, 'Post-Medieval Archaeology' in Chatham and London: The Changing Face of English Land Fortification 1870-1918, , Vol. 19, (1985), 105-149
Beanse, A and Gill, R, The London Mobilisation Centres - unpublished gazetteer, 1999,

Source: Historic England

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