Castlefacts³

Thonock Castle Hills

Has been described as a Certain Timber Castle (Ringwork)

There are cropmark/slight earthwork remains

Name	Thonock Castle Hills
Alternative Names	Gainsborough; Geinesburgo; Thonal
Historic Country	Lincolnshire
Modern Authority	Lincolnshire
1974 Authority	Lincolnshire
Civil Parish	Thonock

The medieval ringwork and baileys at Castle Hills Wood survive well as a series of earthwork and buried deposits. Documentary research and archaeological survey mean that the site is quite well understood. The artificially raised banks will preserve evidence of land use prior to their construction. Its strategic position and later fortifications demonstrate its continued importance as a feature of the wider medieval landscape. As a high-status residence it contributes to our understanding of the social, economic and military activities of a particular component of medieval society.

The monument includes the medieval ringwork and baileys known as Castle Hills. Located in Castle Hills Wood on a west-facing escarpment overlooking the Trent valley, it is thought to date from the late 11th or mid-12th century. In 1086 Thonock was held by Roger of Poitou and around 1115 by the Count of Mortain. The site, which was referred to as the 'castle of Gainsborough', was granted by King Stephen to William de Roumare, Earl of Lincoln by 1146. In the late 12th and 13th centuries it became an important residence, notably of Edmund Earl of Cornwall, brother of Edward I, and was the centre of a barony. The site remained in residential use into the 15th century and the manor remained a holding of the Duchy of Lancaster until 1563, by which time it had been abandoned.

The monument takes the form of a ringwork with banked and ditched baileys adjoining it to the north and south and a steep scarp to the west. The central area of the ringwork is roughly circular in plan, measuring approximately 20m in diameter, and includes a hollow thought to represent the location of buried building remains such as a hall. The central area is enclosed by a bank and external ditch. The bank measures up to 10m in width and is more pronounced on the southern side of the central area

The ditch is steep-sided, measuring 15m in width, and is also more pronounced on the southern side of the ringwork. Additional defence was provided by another steep sided ditch, up to 5m deep, embanked on both sides, which encloses the southern half of the ringwork.

The northern side of the ringwork is enclosed by a bailey believed to be contemporary with the ringwork. The bailey is semi-circular in plan, the enclosed area measuring approximately 80m east to west, and is surrounded by a ditch with an internal bank. The bank and ditch are more pronounced on the eastern side of the bailey. A narrow entrance at the south east corner of the northern bailey is thought to represent an original access point, while mounds adjacent to the entrance are thought to be the tower foundations of a defensive gateway.

The southern bailey adjoins the south and east sides of the ringwork and is thought to represent a subsequent phase of defensive work. The southern bailey is kidney-shaped in plan, and the enclosed area measures approximately 140m north east to south west and is surrounded by a deep ditch with a high internal bank standing up to 5m above the bottom of the ditch. Mounds at the edge of the bailey are thought to represent further tower foundations. A small ditch and bank leads to the south from the south west corner of the bailey. The area immediately to the west and south west of the southern bailey is marked by a series of mounds and hollows thought to represent quarrying for gypsum, an industry associated with the manor during the 14th century. The western boundary of the monument is marked by an artificially enhanced west-facing scarp. (Scheduling Report)

The site is notable as an early military stronghold, a lordly residence and a major estate centre. The tactical and strategic position of the castle is very strong. This overtly military aspect, though again significant in the mid 12th century, perhaps makes it likely that the origin of the castle in its present form belongs to the immediate post-1066 period. On the other hand it is also possible that the castle was erected or at least enlarged or altered in the mid 12th century. In 1086 Thonock was held by Roger of Poitou and around 1115 by the Count of Mortain. It seems likely that the 'Castle of Gainsborough' which was granted to William de Roumare, earl of Lincoln, by King Stephen probably in 1142, is to be identified with this site. Only in the late 12th or 13th century, as part of the Honour of Lancaster, does the site appear to become a principal residence and the centre of a barony. The earthworks consist of a substantial ringwork flanked on both the north and south by outer baileys of more than one period. The first phase was probably the ringwork and the north bailey. The former consists of a steep-sided circular rampart standing up to 5.5m above the bottom of the surrounding ditch and with traces of internal buildings. The tongue-shaped bailey is surrounded by a ditch, reinforced on the east by a broad inner bank standing 4m above the bottom of the ditch, with a possible narrow entrance at the north-east. Additional defensive earthworks along the south side of the ringwork, consisting of a crescentic outer ditch flanked by banks 3 to 4m high, may perhaps be contemporary, or may belong to the second phase of development. This second phase was the addition of the south bailey, a kidney-shaped area enclosed by a massive bank 2.75m high and 5m above a wide outer ditch. Irregularities on the bank may reflect later damage, but could have been caused by the removal of masonry structures, and mounds at the north-west and north-east corners of the bank could represent the sites of former towers or turrets. (Lincolnshire HER ref, Everson, Tayloer and Dunn 1991)

A medieval ringwork and baileys known as Castle Hills, located in Castle Hills Wood. It is thought to date from the late 11th or mid 12th century, and the site may have been location of King Sweyn of Denmark's winter camp, known as "Danish Camp". The monument takes the form of a ringwork with banked and ditched baileys adjoining it to the north and south. The central area of the ringwork is roughly circular in plan, measuring 20 metres in diameter, and includes a hollow thought to represent the location of buried building remains such as a hall. The central area is enclosed by a bank and external ditch. The bank measures up to 10 metres in width and the steep-sided ditch measures 15 metres in width. The northern side of the ringwork is enclosed by a bailey and believed to be contemporary with the ringwork. The bailey is semi-circular in plan, the enclosed area measuring 80 metres east to west, and is surrounded by a ditch with an internal bank. The southern bailey adjoins the south and east sides of the ringwork and is thought to represent a subsequent phase of defensive work. The southern bailey is kidney-shaped in plan, and the enclosed area measures 140 metres north east to south west and is surrounded by a deep ditch with a high internal bank. (PastScape)

Gatehouse Comments

Supposedly retrospectively licensed to crenellate in 1146 (Round dated this 1142 but that date is now considered unlikely), but this is actually a royal confirmation of Earl William of Lincoln possession of the castle. The castle is quite a way outside Gainsborough (1.4km from the parish church) and the bridge over the Trent (1.6Km from its likely medieval location). It is located on a hill overlooking the town and river but such supposedly tactical consideration of placing castles on hills are generally quite rare and it is much more common for castles to be within towns. What was the reason for choosing to locate the castle here? Where there some pre-existing defensive earthworks? Where these Danish? (There are further questions about this as a supposed location of a Danish camp as it is some way from the Trent where the Danish long ships would have been laid up and not the usual form of such Danish winter camps which normally were beside the river protecting the ships). Gainsborough was a separate manor from Thonock with its own manor house, beside the church. In 1066 Thonock was held by Sperri and may have been the caput of his small holdings of seven manor in the local area. In 1086 is was held by Roger of Poitou, who had 600+ manors in East Anglia, the East Midlands and the North-West. If Roger maintained Thonock as a caput for his holdings in north Lincolnshire then he certainly had the wealth to build a large castle here which, while not in Gainsborough itself, would have ready access to the Trent and the transport links that river offered.

- Philip Davis

This site is a scheduled monument protected by law

Not Listed

Historic England (PastScape) Defra or Monument number(s)

325070

County Historic Environment Record

www.heritagegateway.org.uk/Gateway/Results_Single.aspx?uid=MLI54187&resourceID=1006

OS Map Grid Reference	SK818915
Latitude	53.4140815734863
Longitude	-0.770160019397736
Eastings	481840
Northings	391510