A single trial-trench, 4m by 4m in area, was machine-excavated under archaeological supervision within the footprint of a new extension, to be constructed with piled foundations (CBC planning application 152797).<1> The trench was excavated to a depth of 1m and before being stepped so that a 1.8m wide strip down the centre of the trench was excavated down a further 1.8m. The high water-table meant that the bottom of the trench started to rapidly fill with water. The trench revealed modern soils (L1, 0-1.05m), post-medieval dump (L2, 1.05-1.31m), medieval/post-medieval river silts and gravels (L3-L5, 1.31m-2.24m, starting at 5.45m AOD), and Roman river silts (L6, starting at 2.24m deep, 4.5m AOD). Small quantities of Roman, medieval and post-medieval finds in the river silts, the report suggests, were probably derived from centuries of dumping rubbish on the river edge. The earliest dated find is a reused flint core, residual in L5 (which produced almost exclusively Roman finds), broadly dated as Neolithic/Late Neolithic-Bronze Age. Layers L3-L4 contained finds of medieval and post-medieval date. Among these, there were a few preserved organic finds consisting of pieces of wood and two small pieces of leather (L4 (3)). There was also a small quantity of slag and possibly kiln/furnace lining. Dried waterlogged plant remains dominated the assemblages for each environmental sample. Plants of disturbed ground, damp ground and aquatic plants were represented. Possible food plants were present as one grape (Vitis vinifera L) seed in sample <4> (Roman river silts and gravels), one fragment of marrow/cucumber (Cucurbita/Cucumis sp.) seed in sample <2> (post-medieval river silts) and possible caraway (?Carum carvi L.) seeds in samples <1> and <2> (both post-medieval river silts). No anaerobically preserved organic finds were recovered from L5 or L6.