A ground penetrating radar survey (using an Utsi Electronics type GV10) was undertaken at Lambart's Farm, Colchester, by Tim Dennis and students from the University of Essex, across a group of two ring ditches (one concentric) recorded as crop-marks. Magnetometry and ground resistance surveys were also undertaken of the same area, and the results compared. All three methods detected the ditches, although soil resistance worked most effectively to define the ditches. Linear features were also defined, including a possible enclosure with a curved eastern end containing the double ring ditch, and small anomalies indicative of pits.<1>