Ancient Monuments

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Thunderfield Castle medieval moated site

A Scheduled Monument in Horley, Surrey

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Latitude: 51.1677 / 51°10'3"N

Longitude: -0.1421 / 0°8'31"W

OS Eastings: 529994.866125

OS Northings: 142585.417313

OS Grid: TQ299425

Mapcode National: GBR JJW.LX6

Mapcode Global: VHGSJ.HX85

Entry Name: Thunderfield Castle medieval moated site

Scheduled Date: 9 October 1981

Last Amended: 29 April 1991

Source: Historic England

Source ID: 1013348

English Heritage Legacy ID: 12785

County: Surrey

Civil Parish: Horley

Built-Up Area: Horley

Traditional County: Surrey

Lieutenancy Area (Ceremonial County): Surrey

Church of England Parish: Horne

Church of England Diocese: Southwark


Thunderfield Castle, a name applied to the monument only since the 17th
century, is the site of a medieval moated manor house. The original manor
name of Herewoldsle or Harrowsley is preserved in many of the local
placenames. The monument includes a central rectangular moat island 55m by
40m, a moat 7-8m across with a semi-circular extension on the northern side,
an intermediate bank of earth up to 1.2m high and 8m wide, and an outer moat
averaging 6m across. Small-scale excavation in 1936 confirmed the occupation
of the site during the 13th-15th centuries.
At Thunderfield, the central island is likely to have provided the site for
the main house, while ancillary structures such as stables, storehouses etc
are likely to have stood nearby. The semi-circular extension to the inner
moat is best seen as marking the site of a gatehouse and original approach to
the island. The outer moat appears to have been stream-fed from the south,
unlike the inner moat which was spring-fed. An overflow channel, now infilled,
carried water from the inner moat at its north-west corner. The modern
buildings and bridges within the constraint area are excluded from the
scheduling, although the ground beneath each remains included. Also excluded
is the surface of the access road and the service trench beneath it.

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

Source: Historic England

Reasons for Scheduling

Around 6,000 moated sites are known in England. They consist of wide ditches,
often or seasonally water-filled, partly or completely enclosing one or more
islands of dry ground on which stood domestic or religious buildings. In some
cases the islands were used for horticulture. The majority of moated sites
served as prestigious aristocratic and seigneurial residences with the
provision of a moat intended as a status symbol rather than a practical
military defence. The peak period during which moated sites were built was
between about 1250 and 1350 and by far the greatest concentration lies in
central and eastern parts of England. However, moated sites were built
throughout the medieval period, are widely scattered throughout England and
exhibit a high level of diversity in their forms and sizes. They form a
significant class of medieval monument and are important for the understanding
of the distribution of wealth and status in the countryside. Many examples
provide conditions favourable to the survival of organic remains.

Thunderfield, with its diversity of component parts including a double circuit
of moats, is one of a very small number of complex moated sites in the South
East. The large expanses of undeveloped land within the moats makes the
monument of high archaeological potential, especially in the light of the
small scale excavations which have demonstrated that archaeological remains do
survive in the interior. In addition, historical research has revealed a
considerable quantity of information on the former importance of the manor
centred here.

Source: Historic England


Books and journals
Braun, H, 'Surrey Arch. Coll' in Surrey Arch. Coll, , Vol. 45, (1937)
Title: Ordnance Survey County Series Surrey XLII (NW)
Source Date:

Turner, D., Unpublished M.S., Typescript on file

Source: Historic England

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