This study examines the historic landscape of the South West Peninsula of England during the medieval and early post-medieval periods, analysing variations in the rural landscape in a border region between east Cornwall and west Devon. Settlement and field system patterns have been assessed against aspects of the physical environment, including topography, geology and soils, to determine the extent to which they were influenced or determined by the physical environment. The work itself was undertaken using a Geographic Information System (GIS), principally via a map regression using late 19th-century Ordnance Survey maps. Additional layers of data were added to aid in the partial reconstruction of the medieval landscape, ranging from archaeological and monument surveys, documentary sources to aerial photography. Whilst significant differences in the landscapes of adjoining parts of Cornwall and Devon were identified, the role of major landholders in the region, particularly the Duchy of Cornwall and Tavistock Abbey, are brought to the fore.