As climate change may modify the hydrological cycle significantly, understanding the impact on river flow is important because it affects long-term water resources planning. Here, we describe a high-resolution British assessment of changes in river flows in the 2050s under 11 different realisations of HadRM3. In winter, river flows may either increase or decrease, with a wide range of possible decreases in summer flow. These results should encourage adaptation that copes with a broad range of future hydrological conditions. Copyright © 2011 John Wiley & Sons, Ltd.