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.
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.
