A Roman transport canal into Leicester?

After years of research, Steve Mitchell and John Poulter hypothesise that the Raw Dykes – a double-banked ditch located 2km south of Leicester’s Roman public baths – is a remnant of a navigable Roman canal. Their full results were recently published in Itinera (the journal of the Roman Roads Research Association).

Not much is known about the Raw Dykes. It was first noted in documentary evidence in AD 1322, and the antiquarian William Stukeley suggested in 1722 that it was part of a prehistoric cursus. More recently, though, both Kathleen Kenyon (who excavated it in the 1930s) and John Wacher (in The Towns of Roman Britain) considered the ditch to have been part of an aqueduct bringing water to the Roman baths, and presumably to the rest of Roman Leicester – a view that is still supported by Historic England.

The Raw Dykes, looking north towards Leicester, taken c.1960.

Steve Mitchell and John Poulter, independent researchers who both grew up in Leicester, propose that the channel was in fact part of a navigable canal – an idea briefly floated by Sheppard Frere in his first edition of Britannia: a history of Roman Britain – that had superseded an earlier 1st-century aqueduct.

It was the scale of the Raw Dykes – comparable in size to the Grand Union Canal – that first prompted Steve to begin exploring evidence for such a canal, in archives and libraries, on the ground, from the air, and most recently via LiDAR – a task that has now occupied him for 23 years. John’s involvement has been more recent, and has concentrated on validating the feasibility and water-management arrangements of Steve’s proposals.

Steve and John believe the canal dates to the 2nd century, based on evidence from Wacher’s excavation of the baths, and his subsequent chronology. While investigating the caldarium’s northern apse, Wacher identified a pause in construction at that time, and posited a lack of building material as one possible explanation. Steve and John suggest that the canal was built during this pause to enable boats to bring building stone and other materials into the Roman town from sources of granite to the south-west.

Their survey has also identified apparent traces of the channel at ten sites dotted along a 16km stretch of the upper Soar valley, including two that still hold water, while high-resolution LiDAR was used to confirm that the earthworks were on the same level and had the same shape and dimensions as the Raw Dykes. Both researchers are now confident that there is a case for the existence of a Roman transport canal that once ran into Roman Leicester.

The authors believe that they have taken the research as far as they can, and look forward to others carrying forward investigations into its validity.

Image: John Poulter