South Cornwall represents the westernmost part of the Variscan basement massif in SW England. Field-based investigations into the distribution, geometry, kinematics and relative chronology of post-Variscan deformation have been accompanied by preliminary palaeostress analyses. These indicate three episodes of basement reactivation: (1) Stephanian to Early Permian NNW–SSE extension, (2) Early to Late Permian strike-slip deformation, and (3) Late Permian to Triassic ENE–WSW extension. These data have been used to test and refine previously published models, based upon seismic and well data, of late Carboniferous to Triassic basement reactivation and sedimentary basin development within the Western Approaches Trough. We confirm that NNW–SSE regional extension and reactivation of ENE-striking Variscan thrusts had initiated by the latest Carboniferous, and that ENE–WSW regional extension and dip-slip reactivation of NNW-striking high-angle faults occurred during the Triassic. Permian strike-slip deformation recognized onshore may have contributed to the development of widespread unconformities within the oVshore basins.