Tertiary exhumation of Britain and the western North Sea is interpreted to have taken place in two episodes, each with amplitudes of about 1 km: a Palaeogene phase that principally affected the present onshore Britain (west of the present extent of the Late Cretaceous-Danian Chalk Group), and a Neogene phase that affected both onshore areas and the western North Sea. Consequently maximum burial of Mesozoic and older rocks in the present onshore areas generally occurred in the Palaeocene (c. 60 Ma). In the western North Sea, the preservation of the Chalk Group today suggests relatively stable conditions prevailed immediately after its deposition rather than substantial Palaeocene exhumation. In this area, maximum burial is interpreted to have occurred in the Neogene. The proposal is consistent with published exhumation estimates based on studies of sediment compaction (offshore) and of fission tracks (onshore). It also does away with unlikely high burial rates which are implied in the latest Cretaceous-earliest Tertiary if removal of overburden from the Chalk is assumed to have occurred in the Palaeocene.