Farming can be shown to have spread very rapidly across the British Isles and southern Scandinavia around 6000 years ago, following a long period of stasis when the agricultural ‘frontier’ lay further south on the North European Plain between northern France and northern Poland. The reasons for the delay in the adoption of agriculture on the north-west fringe of Europe have been debated by archaeologists for decades. Here, we present fresh evidence that this renewed phase of agricultural expansion was triggered by a significant change in climate. This finding may also have implications for understanding the timing of the expansion of farming into some upland areas of southern and mid-latitude Europe.