A watching brief was carried out during groundworks in the south-east corner of Colchester Castle bailey to add a small extension to the pre-existing floodlight bunker located there. The extension measured 2.8m by 1.25m and was cut through 0.1-0.35m of modern topsoil (L1) onto a post-medieval silty soil (L3). The groundworks revealed a modern topsoil layer, a pot-medieval soil layer, a modern cable trench (2001), and a post-medieval pit. Interestingly, a small quantity of human bone was identified both unstratified and within the post-medieval subsoil layer. A number of inhumation burials are known from within the bailey, possibly dating to the late 16th and 17th centuries when the keep was used as a gaol, and those who died in custody were buried adjacent to the keep. It is likely that the bone recorded during the groundworks was disturbed from nearby graves. <1>