Beneath Quayside: how the riverbank was made

Where the evidence comes from

Most of this account draws on an archaeological investigation carried out at 24 Thompson's Lane, the street behind Quayside, by the Cambridge Archaeological Unit before the plot was redeveloped. This is physical evidence from a single plot. It tells us about that site and what immediately surrounds it, rather than every corner of the modern square.

A wet riverside

The lowest deposits were river-laid silt, or alluvium, which accumulated from prehistoric times until the 14th century. A markedly drier phase during the Roman period was identified by the archaeologists. That is evidence about the ground. It doesn't prove Roman docks or buildings stood here.

Reclaiming the riverbank, 14th to 16th centuries

From the 14th to the 16th century, people spread layer after layer of material to lift and firm up the wet ground. The excavation report calls this gradual reclamation. Parts of the riverbank around Quayside had to be made usable this way, rather than simply being found dry.

The King's Ditch changes course

The King's Ditch marked the edge of the medieval town. At Thompson's Lane it first ran close to the southern side of the excavated plot. In the late 13th century it seems to have been recut on a fresh line near the plot's northern boundary.

Between 1607 and 1609, with St John's College owning the land on both sides, the newer channel was backfilled and the earlier route brought back. So the ditch changed course at least twice.

The dig shows the ditch's course inside and next to this one property. It can't prove the route across today's Quayside square.

Building on the new ground

Once the boundary had changed, standing structures were cleared, and the reclaimed ground joined a broader phase of riverside development in the early 17th century. The general layout of buildings fixed at that time survived, with rebuilding and alteration, into the early 20th century.

Brewers, 1788 to 1902

From 1788 to 1902 the investigated property was in the hands of brewers. In those years its buildings were altered for brewing, storage and other commercial uses, as the riverside economy shifted.

Before it was Thompson's Lane

According to an archaeological assessment, Thompson's Lane went by the name Harlestone Lane in the medieval period.

What this does and does not show

It shows river silts building up into the 14th century, deliberate reclamation between the 14th and 16th centuries, a boundary ditch that shifted at least twice, and over a century of brewing.

It does not show a Roman dock at Quayside, a dock used without a break for 2,000 years, or the King's Ditch's path across the present square. Today's buildings around Quayside are mostly a modern development, not surviving dock warehouses.

For the bigger picture, read the history of Quayside, the story of the crossing at Magdalene Bridge, and the older settlement on Castle Hill.

Sources

• Richard Newman, 24 Thompson's Lane, Cambridge: An Archaeological Investigation, Cambridge Archaeological Unit. Used for the river silts, the reclamation, the King's Ditch, the early 17th century development and the brewers.
• Cambridgeshire County Council Archaeological Field Unit, Report A233, Thompson's Lane. Used for the medieval name Harlestone Lane.

Sources checked October 2026.