Sleaford Castle


Heritage Category:
Scheduled Monument
List Entry Number:
Date first listed:
Date of most recent amendment:


Ordnance survey map of Sleaford Castle
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The building or site itself may lie within the boundary of more than one authority.

North Kesteven (District Authority)
National Grid Reference:
TF 06456 45558

Reasons for Designation

An enclosure castle is a defended residence or stronghold, built mainly of stone, in which the principal or sole defence comprises the walls and towers bounding the site. Some form of keep may have stood within the enclosure but this was not significant in defensive terms and served mainly to provide accommodation. Larger sites might have more than one line of walling and there are normally mural towers and gatehouses. Outside the walls a ditch, either waterfilled or dry, crossed by bridges may be found. The first enclosure castles were constructed at the time of the Norman Conquest. However, they developed considerably in form during the 12th century when defensive experience gained during the Crusades was applied to their design. The majority of examples were constructed in the 13th century although a few were built as late as the 14th century. Some represent reconstructions of earlier medieval earthwork castles of the motte and bailey type, although others were new creations. They provided strongly defended residences for the king or leading families and occur in both urban and rural situations. Enclosure castles are widely dispersed throughout England, with a slight concentration in Kent and Sussex supporting a vulnerable coast, and a strong concentration along the Welsh border where some of the best examples were built under Edward I. They are rare nationally with only 126 recorded examples. Considerable diversity of form is exhibited with no two examples being exactly alike. With other castle types, they are major medieval monument types which, belonging to the highest levels of society, frequently acted as major administrative centres and formed the foci for developing settlement patterns. Castles generally provide an emotive and evocative link to the past and can provide a valuable educational resource, both with respect to medieval warfare and defence and with respect to wider aspects of medieval society. All examples retaining significant remains of medieval date are considered to be nationally important.

Sleaford Castle is rare in being one of only three enclosure castles in Lincolnshire, and one which was both constructed and maintained under episcopal control. As a primarily administrative rather than military establishment it includes examples of distinctive structures, such as the manorial barn and constable's house, rarely associated with this type of monument. The remains of the castle survive well as a series of substantial earthworks and buried features which have never been excavated, suggesting the survival of structural features, artefacts and ecofactual deposits; in particular, waterlogging in the area of the moats will result in a high level of survival for organic remains. Diverse features are evident which, as a result of detailed historical research, are quite well understood. The remains represent a limited period of occupation and are relatively undisturbed by later activity; they will thus preserve valuable evidence for the construction and use of the castle, and contribute to our knowledge of medieval society, technology and economy. As a monument open to the public, Sleaford Castle also serves as an important recreational and educational resource.


The monument includes the remains of Sleaford Castle, an enclosure castle built in the early 12th century by Alexander, Bishop of Lincoln. Following a brief period of surrender to King Stephen in 1139 it was held by successive bishops for over 400 years, serving as an administrative centre for the episcopal estates in the Sleaford area. In the 15th century it was partially rebuilt by Bishop Alnwick, and in 1547 was transferred by Bishop Holbeach to Edward, Duke of Somerset. After this date it became a source of building materials and was progressively dismantled. In 1720 parts of the walls and towers were still standing; now the only fragment of masonry surviving above ground is part of the north eastern corner tower. The monument includes the standing remains of this tower and the earthworks and buried remains of the remainder of the castle.

Sleaford Castle is situated on the edge of the medieval parish of New Sleaford about 500m south west of the town centre. It is surrounded on all sides by low lying land, formerly waterlogged, including part of Sleaford Fen. The castle was built in this area of wet land by constructing raised earthwork baileys surrounded by water channels. The remains of the castle take the form of a series of substantial earthworks, including three raised areas: a large L-shaped outer bailey which was defended solely by water; a quadrangular inner bailey, defended by both water and a curtain wall; and a broad outer bank of linear form. The earthwork remains of these features and the moats which surrounded them occupy a roughly rectangular area on the south bank of the Nine Foot River.

The outer bailey is approached from the north western corner of the monument along a raised trackway, on the site of a former bridge, representing the original entrance to the castle. The outer bailey, which is of L-shaped plan, occupies the south western half of the monument; the western arm is approximately 55m long, the southern 60m, and both are between 15m and 20m in width. In the outer bailey are the earthwork and buried remains of agricultural and domestic buildings associated with the castle's function as the centre of a manorial estate. Principal among these are the remains of the manorial barn, a large rectangular structure aligned roughly east-west in the southern part of the bailey. The walls are visible as low earthworks defining an area nearly 50m long and over 15m wide. Documentary sources of the 14th to 16th centuries record the storage here of produce from the episcopal estates. Adjacent to the north east of the barn is a circular depression 1m deep surrounded by buried walls 0.5m high; this is believed to represent the remains of a circular dovecote, also known through documentary sources. Attached to the west side of the barn are the buried foundations of a smaller rectangular building approximately 20m long and 10m wide, believed to be the remains of a byre. In the western part of the outer bailey are further slight earthworks believed to represent the hall of the constable, who managed the castle on behalf of the bishop, and associated outbuildings such as stables.

The outer bailey is surrounded by the remains of two moats which were fed from the river to the north. On the south and west sides are the remains of the outer moat, a linear depression up to 30m wide and 2m deep. It survives in two parts: the southern arm, now dry, lies in the south eastern part of the monument; the western arm, also dry, is now occupied by public play equipment which is not included in the scheduling although the ground beneath it is included. The two arms of the moat formerly met at the south western corner of the outer bailey in an area outside the monument now occupied by the railway. On the north east side of the outer bailey are the remains of the castle's inner moat, also L-shaped. It is a dry, flat-bottomed depression up to 20m in width. Both the outer and inner moats are linked on the north to the earthwork remains of a further moat, constructed on the course of the river, which survives as a dry depression about 10m wide and stands up to 1.5m above the modern river channel which cuts along its northern edge. In the eastern part of the monument the outer and inner moats are linked to a linear moat aligned north-south, about 20m wide and still partially water filled, through which they drained back into the river.

In the northern part of the monument, surrounded by moats, are the remains of the castle's inner bailey. It is reached from the northern end of the outer bailey by a raised trackway which crosses the inner moat on the site of a former bridge. The inner bailey occupies a quadrangular area, approximately 80m by 60m, around the edge of which are the earthwork and buried remains of a curtain wall; deep linear trenches indicate where the limestone was robbed for reuse in the post-medieval period. In the north western part of the inner bailey, at the approach from the outer bailey, are the remains of the outer gatehouse, including two square depressions representing ground floor chambers, one on each side of the curtain wall. The outer gate is known through documentary sources to have had two portcullises. Also along the curtain wall are the earthwork remains of mural towers; at the north eastern corner is a large piece of standing masonry, partly fallen inwards and supported by two concrete pillars, which has been interpreted as part of a corner tower. The area enclosed by the curtain wall is divided into two rectangular courts by the earthwork remains of a further wall, at the north end of which are the earthworks of two substantial chambers, one on each side of the wall; these are believed to represent the inner gatehouse, also known through documentary sources. The area to the west of the dividing wall is otherwise mainly level and represents an outer court, largely open apart from some ancillary buildings such as the brewhouse. The area to the east of the wall contains a substantial series of earth covered walls and partially infilled depressions representing the remains of the main buildings of the castle, including the keep and chapel, and their basement storage chambers.

On the eastern edge of the monument, separated from the inner bailey by a moat, is a broad linear bank about 10m wide and 110m long. The top of the bank is flat and stands about 1m above the moat on its western side and 2m above the modern drain on the east. This bank, which forms an integral part of the defended earthworks of the castle, is interpreted as the site of the castle orchard or fruit garden described in documentary sources.

All fences and and posts 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.


The contents of this record have been generated from a legacy data system.

Legacy System number:
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Books and journals
Sleaford Castle, (1990)
Toulmin Smith, L, The Itinerary of John Leland in or about the Years 1535-1543, (1964), 26-27
Pawley, S, 'Watergate and Westgate: The Castle Area' in Sleaford Trails, , Vol. 2, (1990)
Trollope, E, 'LAASRP' in LAASRP, , Vol. 7, (1864), 73-78
Extent of the Castle & Manor of Sleaford, 1324 [PRO E142/32/11], unpublished transcription by S Pawley
Hussey vs. Carre (Star Chamber) -- around 1556-9 [PRO STAC4/3/8], unpublished transcription by S Pawley
LAO BP/ACCTS/19 - Repairs at Sleaford Castle 1509-10, unpublished transcription by S Pawley
Pawley, Simon,
Repairs at Sleaford Castle 1509-10 [LAO BP/ACCTS/19], unpublished transcription by S Pawley
unpublished transcription by S Pawley, Compotus of Sleaford, 1323-4 [PRO SC6/913/8-9],
unpublished transcription by S Pawley, Hussey vs. Carre (Star Chamber) - around 1556-9 [PRO STAC 4/3/8],


This monument is scheduled under the Ancient Monuments and Archaeological Areas Act 1979 as amended as it appears to the Secretary of State to be of national importance. This entry is a copy, the original is held by the Department for Digital, Culture, Media and Sport.

End of official listing

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