Buckinghamshire Grim's Ditch: 1.13km long section from Grymsdyke Manor to RAF High Wycombe


Heritage Category: Scheduled Monument

List Entry Number: 1020884

Date first listed: 19-Aug-1936

Date of most recent amendment: 09-Sep-2003


Ordnance survey map of Buckinghamshire Grim's Ditch: 1.13km long section from Grymsdyke Manor to RAF High Wycombe
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The building or site itself may lie within the boundary of more than one authority.

County: Buckinghamshire

District: Wycombe (District Authority)

Parish: Bradenham

County: Buckinghamshire

District: Wycombe (District Authority)

Parish: Lacey Green

National Grid Reference: SU 82830 99136


Legacy Record - This information may be included in the List Entry Details.

Reasons for Designation

Linear boundaries are substantial earthwork features comprising single or multiple ditches and banks which may extend over distances varying between less than 1km to over 10km. They survive as earthworks or as linear features visible as cropmarks on aerial photographs or as a combination of both. The evidence of excavation and study of associated monuments demonstrate that their construction spans the millennium from the Middle Bronze Age, although they may have been re-used later. The scale of many linear boundaries has been taken to indicate that they were constructed by large social groups and were used to mark important boundaries in the landscape; their impressive scale displaying the corporate prestige of their builders. They would have been powerful symbols, often with religious associations, used to define and order the territorial holdings of those groups who constructed them. Linear earthworks are of considerable importance for the analysis of settlement and land use in the Bronze Age; all well preserved examples will normally merit statutory protection.

The feature known as the Buckinghamshire and Hertfordshire Grim's Ditch includes a series of three prehistoric linear earthworks aligned along the scarp face of the Chiltern Hills between Bradenham and Berkhamstead, and together spanning some 18km. It does not appear that these principal sections were ever joined to form a continuous boundary. Current evidence suggests that the sometimes quite sizeable gaps represent areas which were formerly forested or in which natural features served to perpetuate a division of the land. The same pattern has been discerned along the North Oxfordshire Grim's Ditch, a separate monument to the west of the River Thames. A further comparable linear boundary, the Moel Ditch, extends to the east across parts of neighbouring Bedfordshire. For the most part the visible sections of Grim's Ditch in the Chilterns include a wide single ditch flanked on the south side by a bank of upcast earth overlying a turf core. Excavations, carried out in 1973 and 1991 in the parishes of Tring and Northchurch, Hertfordshire, identified a berm between the bank and ditch over which the bank later spread. In one excavation a narrow trench, possibly dug to support a palisade or fence, was discovered along the edge of the ditch furthest from the bank. The Buckinghamshire and Hertfordshire Grim's Ditch is thought to have served as a territorial boundary, separating, and perhaps enclosing, organised groups of land and settlement. It may also have been an agricultural boundary, denoting grazing areas and impeding the movement (or theft) of stock. Excavations to date have provided only limited dating evidence. Pottery recovered from the fill of the ditch indicates that it was in existence in the Iron Age, although it may have a considerably earlier origin. As such, the boundary provides important evidence for the management of the landscape in the centuries preceding the Roman Conquest in AD 43. It remained a notable feature in later centuries, acquiring its present name (a variation on the name of the god, Odin) at some time in the early medieval period, perhaps during the period of the pagan Saxon settlement in the 5th and 6th centuries. The earliest recorded use of the term `Grim's Ditch' occurs in a charter granted by Edward, Earl of Cornwall in 1291. All sections of the Buckinghamshire and Hertfordshire Grim's Ditch which survive in visible form or as well-preserved buried remains (identified by aerial photography or ground survey) are considered integral to a general understanding of the monument and will normally merit statutory protection. This 1.13km section of Grim's Ditch from Grymsdyke Manor to RAF High Wycombe survives well as a visible earthwork along most of its length and provides a valuable insight into the nature of early territorial land division in the Chiltern Hills. It will contain archaeological evidence for the manner of its construction as well as environmental evidence for the appearance of the landscape in which it was built. The archaeological evidence may also include either artefacts or scientific dating material from which to determine the period of its construction and the duration of its maintenance as an active boundary. The majority of surviving pillboxes in England date from the period immediately before and during World War II. A variety of types were developed for use in a wide range of contexts which included the close defence of military installations such as dockyards, gun emplacements and airfields, as well as the more general defence of the coastline and, from 1940 onwards the provision of stop lines designed to halt or at least delay the progress of a potential German invading force. The well-preserved brick pillbox built against the bank of Grim's Ditch at RAF High Wycombe was intended for the close defence of the Bomber Command Headquarters, established here in 1940. It provides a graphic illustration of the measures taken to secure this highly significant airforce base, which included the reuse of the prehistoric dyke within the defensive perimeter.


Legacy Record - This information may be included in the List Entry Details.


The monument includes a 1.13km long section of a prehistoric boundary known as the Buckinghamshire Grim's Ditch, which is located on high ground between West Wycombe and Lacey Green and runs broadly north west-south east to the west of and parallel with New Road. The boundary survives as a clearly visible bank and ditch along most of this length. The northern section, from Grymsdyke Manor to RAF High Wycombe, includes an earthern bank, 9m wide and standing up to 1.2m high. To the east of the bank lies a parallel ditch, approximately 8.8m wide and up to 0.7m in depth. Excavations along other sections of Grim's Ditch, carried out in 1973 and 1991, produced evidence of a level area, or berm, separating the bank and ditch. Evidence for a palisade trench, which would have supported a wooden fence, was also found along the outer edge of the ditch. These components may also survive as buried features along this section of the Grim's Ditch. The southern 300m section of this length of Grim's Ditch lies within the Headquarters of NATO Strike Command, RAF High Wycombe. Despite some disturbance, the monument is visible as a well-preserved bank and ditch. Within this area a single World War II pillbox has been built against the west side of the bank of Grim's Ditch and is included in the scheduling. The pillbox is a sub-square brick and concrete chamber with a concrete slab roof, measuring approximately 4 sq m. An external wall along the north west side provides protected access to the entrance on the north west corner. Inside there is a central cross-shaped ricochet wall. All four sides of the pillbox are identical and display a central machine gun portal with a wooden unipod mounting, flanked by two rifle loops. A number of features are excluded from the scheduling. These are: all fences, road surfaces, signs, telegraph poles, paving stones, notices and services, and within the RAF base the iron bailey bridge, walls, fuel tanks, the sanger, parallel bars, lamp posts, the concrete footbridge carrying services across the ditch, the weapons discharge pit and weapon discharger, concrete post and wooden panel fence and man holes. The ground beneath all these features, however, 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.


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

Legacy System number: 35332

Legacy System: RSM


Books and journals
Network Archaeology, , Grim's Ditch: Archaeological and Management Survey Phase III, (1999)

End of official listing