The development of Permian to Cretaceous sedimentary basins in southern Britain was profoundly controlled by the extensional reactivation of Caledonian and Variscan structural features. Analysis of fault kinematics and basin geometries indicates that Permian to early Jurassic basins developed within a region of roughly east-west continental extension, as Pangea was stretched. In late Jurassic and early Cretaceous times regional east-west extension continued, but the sedimentary basins of southern England developed a different structural aspect, suggestive of more northward-directed extension, probably related to rotation of Iberia and opening of the Bay of Biscay. Two plate-tectonic reconstructions for end-Carboniferous time are examined. One is based on a best fit of apparent polar wander path data; the other is a best fit of present-day continental-shelf isobaths. The former requires 42% continental extension between Europe and Canada prior to the onset of sea-floor spreading in mid-Cretaceous times, whereas the latter requires only 16% extension prior to the onset of seafloor spreading. Preserved sediment thicknesses and seawater depths on the continental shelves of northwestern Europe and eastern Canada indicate that an end-Carboniferous plate reconstruction based on the fit of shelf isobaths is most appropriate.