Brinkley Grove is a wooded area in the northern suburbs of Colchester and forms part of Highwoods Country Park. Within this woodland is a large earthwork (NHLE number 1002137) in the form of a substantial L-shaped ditch (approximately 15m across), thought possibly to represent part of a large enclosure. Earth mounds on parts of the inner ditch edge may indicate an internal bank, and there are signs of a counterscarp bank also. The 1841 tythe map shows the area of the monument to have been part of High Wood rather than Brinkley Grove. Two small trenches located at the present northern extent of the earthwork’s west ditch produced no clear evidence for the date or function of the monument, nor for the existence of an inner bank. A small east-west ditch, probably of post-medieval date, crosses this area and is cut though clean sandy clay. This is probably natural subsoil rather than redeposited material filling a former ditch, and the present limit of the ditch is considered to be its original extent. An auger survey demonstrated that the west ditch is certainly not present 35m north of its existing limit. The augering also showed that the natural subsoil of this area is sandy clay. Limited observation of the area of the internal ‘bank’ revealed this to be irregular mounds, which are absent from much of the north-eastern part of the earthwork, and are probably just dumps of upcast soil. A profile of the ditch near the present north terminus indicated the presence of a slight counterscarp mound, though this may also result from upcast soil accumulation and dumping. The monument appears to be of no greater extent on its west side than the present earthwork, and this is probably the case for the monument as a whole. This is supported by interpretation of some documentary (map) sources. The earthwork’s angular L-shaped plan reflects the corner of two boundaries, an existing one to the south and another indicated by a track and mature trees in line with the monument’s west side. However, its chronological relationship with these boundaries is not known, and the southern boundary (probably of relatively recent origin) may post-date the earthwork. The limited evidence suggests that the monument is possibly the result of clay-extraction, and the 1841 tythe map shows field names relating to sand and clay extraction and tile and pottery-making within 0.5km of the earthwork. Further documentary research and augering of the site would help clarify this interpretation. <1>