Welcome to the Risborough Area Portal

  Helping you find all you need to shop, live, work and play.

Grim’s Ditch

Grim’s Ditch…a Chiltern mystery.

While the Icknield Way is almost certainly our oldest historical feature dating back 5,000 years or more, Grim’s Ditch has probably been the most puzzling ancient feature. Locally it can be followed from Hampden House through the woods to Redland End and Lily Bottom, south of the Pink & Lily PH, and then on to Lacey Green. It has been the subject of much debate and conjecture over the centuries and not until the 1970s was its true age, if not its purpose, finally confirmed.

The Chiltern Grim’s Ditch is a series of linear earthworks running for 20 miles between Ivinghoe Beacon to Bradenham and then found again in south Oxfordshire where sections survive between Nettlebed and the River Thames at Mongerwell near Wallingford. The most striking sections can be found running down to the Thames from Nettlebed and north of Cholesbury.

Its size varies considerably, probably as a result of local erosion, root disturbance and tree throws as well as infill. However sections near Cholesbury display a ditch up to 12ft wide and 8ft deep with a bank 7ft high. The full width of the feature is up to 50ft in places but all these present day measurements probably disguise its original statue. The bank will always be found on the escarpment or western side with the ditch alongside facing the south or east.

Over the years historians struggled to date the ditch particularly as it lacked any direct association with known archaeology in the Chilterns, following an often remote and rural course away from settlements. Consequently it was variously ascribed as being of Roman, Saxon, Norman or even Medieval in origin. Fanciful explanations included its construction as an anti chariot defence, quickly thrown up upon news of the arrival of the Romans!  Clearly implausible and hardly an effective deterrent against the might of Rome!

However in the 1970s, archaeological investigations ahead of the new A41 Berkhamsted bypass which would breach a length of Grim’s Ditch near the Cow Roast, revealed its true age and this was subsequently confirmed at other locations. Pottery shards confirmed that its origin was in the Iron Age with construction around 300BC, the period just prior to the arrival of the Romans. Interestingly, the first documented mention of Grim’s Ditch is in a grant of 1170–90 in the Missenden Cartulary referring to it as Grimesdic. Another mention is to be found in a 10th-century Anglo Saxon boundary charter for the Mongewell area near Wallingford.

Despite this confirmation of its date, the purpose of Grim’s Ditch may always remain a mystery. Its route through the Chilterns from Ivinghoe Beacon to Wallingford is by no means continuous with frequent gaps in the Buckinghamshire beechwoods and no obvious evidence between Bradenham and Nettlebed. Investigations in recent years around Lacey Green concluded that no ditch feature was buried in the notable gaps in that parish which tends to suggest that either the feature was abandoned before completion or it was never intended as a continuous ditch and bank. One strikingly unusual aspect are the two locations where Grim’s Ditch turns sharply at exactly 90 degrees, firstly in the woods between Hampden House and Redland End and then near Stocken Farm, Lacey Green. We will probably never know why!

What is known is that Grim’s Ditch would have been constructed in a landscape almost devoid of trees and clear of scrub. This offered the builders clear lines of site when creating the straight sections. Its most likely purpose is a boundary to control the movement of livestock and people and almost certainly not having a defensive function due to its length and style of construction.  It may have defined areas for grazing. It has also been suggested that the ditch recognised a pre-roman tribal boundary between the Catuvellauni whose capital was close to St Albans, and the peoples to the west.

And how did it get its name? The Anglo Saxons commonly named features of unexplained or mysterious origin Grim. The word derives from the Norse word grimr meaning devil and a nickname for Odin or Wodin the God of War and Magic. Across southern England and beyond numerous ancient features share this name. Grim’s Ditches exist in Berkshire, Hampshire, Oxfordshire and Hertfordshire, The Antonine Wall which once separated Scotland from Roman Britain is also sometimes known as Graham’s Dyke. In Suffolk, a large Neolithic flint mine is known by the name of Grimes Graves.The Grim Reaper is also thought to be one of W?den’s manifestations.

Today we can all enjoy the Chiltern sections of Grim’s Ditch which offer wonderful walks through our beechwoods, across open commons and along downland ridges, as we step back over 2000 years in time.


Francis Gomme

Risborough Countryside Group