The present disclosure relates to a controller (2) for identifying a periphery of a towed vehicle (T) connected to a towing vehicle (V). The controller (2) is configured to receive towing vehicle image data (DV1) corresponding to a towing vehicle image (IMG1) captured by a towing vehicle camera (C1). The towing vehicle image data (DV1) is processed to generate a plurality of movement vector. The periphery (P1) of the towed vehicle (T) is identified in dependence on the plurality of movement vectors. The present disclosure also relates to a method of identifying the periphery (P1) of a towed vehicle (T).