The Royston Mile Ditches and other Iron Age multiple-ditched territorial boundaries on the Icknield Belt in the eastern Chilterns

By Gil Burleigh

Black and White picture - Major G Allen, 1934, ( copyright of  the Ashmolean Museum, Oxford)

Black and White picture - Major G Allen, 1934, (© The Ashmolean Museum, Oxford)

The three parallel Iron Age ditches known as the Mile Ditches run from Therfield Heath in Hertfordshire to Bassingbourn Springs in Cambridgeshire, a distance of about three kilometres. Originally the ditches had accompanying banks formed by the upcast from the ditches. The banks possibly supported timber palisades, making the monument a formidable obstacle across the line of the Icknield Way and controlling the movement of people and animals. The Mile Ditches were one of a series of such Iron Age ditch systems lying across the Icknield Belt between Luton and Royston. These ditch systems appear to have defined territories related to hill-forts, such as Ravensburgh Castle, Wilbury Hill and Arbury Banks.

The Mile Ditches, 8 March 1978, looking north-west

The Mile Ditches, 8 March 1978, looking north-west (photograph G R Burleigh © NHDC)

The Mile Ditches were excavated in advance of the dualling of the A505 in 1978. The primary silt of the western ditch of the three Mile Ditches has been dated to the second century BC. The ditches have been shown to have silted up very slowly over two millennia before being finally completely filled, on the Cambridgeshire side in the early 1800s and on the Hertfordshire side in the 1940s, when the surviving banks were levelled into the ditches. A second series of multiple ditches running parallel with the line of the Icknield Way between Baldock and Royston has been interpreted as helping to define the territory of the Late Iron Age oppidum at Baldock.

General view of the Mile Ditches excavation, 5 March 1978

General view of the Mile Ditches excavation, 5 March 1978 (photograph G R Burleigh © NHDC)


S Bryant & G Burleigh 1995 ‘Later prehistoric dykes of the eastern Chilterns’

G Burleigh 1995 ‘A late Iron Age oppidum at Baldock, Hertfordshire’

(both the above papers are in R Holgate, see below)

G Burleigh 1980 ‘The Mile Ditches, near Royston: Excavations, 1978’ in Hertfordshire’s Past no.8

O G S Crawford 1936 ‘Field Archaeology of the Royston District’ in Proceedings of the Prehistoric Society vol. 2

J F Dyer 1961 ‘Dray’s Ditches, Bedfordshire, and Early Iron Age territorial boundaries in the Eastern Chilterns’ in Antiquaries Journal vol. 41

R Holgate (ed.) 1995 Chiltern Archaeology: Recent Work: a handbook for the next decade. Dunstable: The Book Castle

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