In a changing climate it is important to understand how all components of the climate system may change. For many impact sectors, particularly those relating to flooding and water resources, changes in precipitation intensity and amount are much more important than changes in temperature. This study assesses possible changes in extreme precipitation intensities estimated through both quantile and return period analysis over Britain. Results using a regional climate model (with greenhouse gas changes following the IS92a scenario for 2080-2100) indicate dramatic increases in the heaviest precipitation events over Britain. The results provide information to alter design storm intensities to take future climate change into account, for structures/projects that have long life times.