During excavations at Balkerne Lane between 1973-6 (ECC332) a late Roman ditch was discovered. The ditch was placed along the eastern edge of the late Roman town ditch (see MCC659) running north-south so that it passed along the foot of the possible shrine (MCC557) and the cella of the Romano-Celtic temple (MCC556). The ditch clearly post dated the robbing of the foundation of the ambulatory of the temple as it crossed the robber trenches of the north and south walls. These robber trenches were no earlier than the mid 4th century.

The ditch varied in depth between 0.5 and 0.8m but its original depth could not be established due to the destruction of the latest levels on the site from 19th century terracing. The purpose of the ditch is unknown but the excavators felt that a defensive role was likely. A second north-south ditch was located to the north (MCC627) but 'it is unlikely that both ditches were conceived as part of the same scheme'.<1>