Details

The monument falls into two separate areas and includes the main compound and
tool store of East Merstham mobilisation centre, known as Alderstead Fort,
situated on a chalk ridge of the Surrey Downs.
The main compound forms the south western part of the monument and houses a
three-roomed magazine fronted by five casemates. It survives as a roughly
north west-south east aligned, north east facing, flat-roofed structure
constructed mainly of reinforced concrete and brick, with a large, crescent-
shaped earthen blast-bank partly covering and flanking the magazine to the
rear. Beyond the bank is an up to 10m wide ditch. The building retains many
original fittings, including iron-and-wood door and window shields and
magazine vents.
The associated red-brick tool store lies around 75m to the north east and is
a north east-south west aligned, single storey, rectangular building measuring
14m by 10m, with white washed sandstone dressings under a pitched, blue slate
roof. The south eastern face has full-length, central double doors flanked by
tall windows with iron grilles. The original caretaker's lodge, situated
around 40m to the north east, is in use as a dwelling and is therefore not
included in the scheduling.
The modern lean-to structures at the north western end of the main compound
are excluded from the scheduling, although the ground beneath them is
included.

MAP EXTRACT
The site of the monument is shown on the attached map extract.
It includes a 2 metre boundary around the archaeological features,
considered to be essential for the monument's support and preservation.

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.

Unusually for this type of monument, Alderstead Fort has remained largely free
of alteration or renovation and, despite some natural decay and woodland
regeneration, survives comparatively well. Architectural survey has shown that
the monument retains evidence relating to the construction and use
of mobilisation centres.

Source: Historic England

Sources

Books and journals
Smith, V, 'London Archaeologist' in The London Mobilisation Centres, , Vol. 2, 10, (1975), 244-248
Other
Gill, RJ, East Merstham Mobilisation Centre, 1995, unpublished survey

Source: Historic England