AbstractThe publication of The Clay Mineralogy of British Sediments by Perrin in 1971 collated several decades of clay mineral research in the British Isles and for the first time presented all the data in a stratigraphical framework. While it quickly became a useful source of information for geologists, engineers and soil scientists, it also revealed many gaps in clay mineral data through the geological succession, stimulating further research. Within ten years of publication, a successor to Perrin's book was under discussion by the Clay Minerals Group. Inevitably, the enthusiasm for the concept of the project gave way to the patience of a long gestation. A successor to Perrin (1971) became a standing item on the agenda of Clay Minerals Group Committee meetings, and the bane of many a Chairman's three years in office. By the mid-1990s the project began to show real progress, gathering momentum from the success of an international series of 'Cambridge clay mineral diagenesis conferences' (1981, 1984, 1986, 1989, 1993, 1998) that were supported by the oil industry. A timely injection of financial support from the Joint Association for Petroleum Exploration Courses (JAPEC) ensured a successful conclusion for the project.The cost of publication has been borne by three sponsors: the Clay Minerals Group, JAPEC (UK: training), and the Mineralogical Society. Consequently, the financing of this Special Volume of Clay Minerals is entirely independent of the usual costs of publishing the journal. We owe our particular thanks to Kevin Murphy, Editorial Manager, for his care and humour in guiding Clay minerals in onshore and offshore strata of the British Isles through publication.