The name is derived from the Latin word for a camp, 'castra', indicating that the Roman army may once have been based near here. There is no longer any signs of such an encampment which was thought to have provided protection of the waterway to Tadcaster. The use of Selby indicates that the lands were brought within the control of Selby Abbey. This was done by Osbert de Arches at the time of the Norman Conquest and confirmed in the reign of Richard I.