Beneath Quayside: how the riverbank was made

Where the evidence comes from

Most of what follows comes from an archaeological investigation at 24 Thompson's Lane, the street that runs behind Quayside, carried out by the Cambridge Archaeological Unit ahead of redevelopment. It is physical evidence from one plot. It describes that site and its immediate surroundings, not every part of the modern square.

A wet riverside

The earliest deposits were layers of river-laid silt, known as alluvium, which built up from prehistoric times until the 14th century. The archaeologists identified a noticeably drier phase during the Roman period. That tells us about the ground. It does not show that Roman docks or buildings stood on the site.

Reclaiming the riverbank, 14th to 16th centuries

Between the 14th and 16th centuries, people laid down successive layers of material to raise and firm up the wet ground. The excavation report describes this as gradual reclamation. Parts of the riverbank around Quayside were made usable in this way. They were not simply found dry.

The King's Ditch changes course

The King's Ditch marked the boundary of the medieval town. At Thompson's Lane its original line ran near the southern edge of the excavated plot. In the late 13th century it was apparently recut along a new line near the plot's northern boundary.

Between 1607 and 1609, while St John's College owned the land on both sides, that newer channel was filled in and the earlier route was re-established. The ditch therefore changed course at least twice.

The excavation shows the ditch's course within and beside this one property. It is not proof of its route across the modern Quayside square.

Building on the new ground

After the boundary changes, existing structures were cleared and the reclaimed ground became part of a wider phase of riverside development in the early 17th century. The broad arrangement of buildings set out then lasted, with rebuilding and alteration, into the early 20th century.

Brewers, 1788 to 1902

Brewers occupied the investigated property between 1788 and 1902. Over that time the buildings were adapted for brewing, storage and other commercial uses as the riverside economy changed.

Before it was Thompson's Lane

An archaeological assessment records that Thompson's Lane was known in the medieval period as Harlestone Lane.

What this does and does not show

It shows river silts accumulating into the 14th century, deliberate reclamation from the 14th to the 16th centuries, a boundary ditch that moved at least twice, and more than a century of brewing.

It does not show a Roman dock at Quayside, a dock in continuous use for 2,000 years, or the route of the King's Ditch across the present square. The buildings around Quayside today are largely a modern development, not surviving dock warehouses.

For the wider story, read the history of Quayside, the account of the crossing at Magdalene Bridge, and the earlier 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.