A watching brief was held during the construction of a new sorting office on the east bank of the River Colne, approximately 80m south of the present East Bridge. The highest level of ground disturbance affected an area of 700 sq.m. adjoining the river, where foundation works included excavation of a close-knit grid of stanchion holes up to 2.8m square with centres located at 5m to 7m intervals. Elsewhere the groundworks were less intrusive consisting mainly of lines of smaller stanchion holes. It was not possible to fully inspect each stanchion hole before concreting and observations were thus based on groundworks inspected at varying stages of completion. No conclusively early features were found. The group of stanchion holes closest to the river contained modern deposits extending to depths between 0.3 and 0.85m. This sealed a sandy loam topsoil which in turn overlaid a natural gravely sand. In the centre of the site two stanchion holes revealed a probable post-medieval layer. Near the northern boundary an area adjacent to Grays Cottages was cut by a medieval or later pit extending to a depth of 2.5m.<1>