A watching brief was undertaken during a Transco gas-main replacement along Crouch Street and St John’s Street. This involved contractors machine-excavating two trenches within the public highway which were typically between 1m and 1.7m in depth. An approximately 360m-long and 600mm-wide trench was excavated from just beyond the junction of Stanwell Street and St John’s Street up to no 1 St John’s Street. The final piece of groundworks was a shorter trench (5m long and over 1m wide) dug outside the old Odeon cinema on Crouch Street. The section in between was not excavated. <1> The typical profile in St John’s Street was tarmac with a stone and asphalt sub-base overlying dark brown silty sand with brick and occasional peg-tile. A very small amount of Roman pottery and tile was found residually within modern layers. The only feature observed was a section of cobbled surface 900mm below ground-level, seen outside 26a St John’s Street. This is assumed to be the old (possibly medieval) road surface of St John’s Street before it was tarmaced. Below the cobbles was a soil layer containing peg-tile which extended to the base of the trench. This was one of the few areas within the trench that had not been previously disturbed by earlier pipe-laying. The trench outside the Odeon was 1.7m deep. It was excavated to locate the existing gas pipe and therefore was dug through backfill. The trench was cut trough tarmac, hogging and concrete. Beneath these modern deposits, dark brown clay slit with brick and tile fragments sealed a metalled/cobbled surface. The surface was 900mm below ground-level. Underneath the surface was 700mm of dark brown clay silt with tile fragments and occasional oyster shell. Like the cobbled surface recorded in St John’s Street, this may be a remnant of a medieval road surface.