Two radiocarbon dates near the beginning and end of the Allerød interstadial (conventional pollen zone II) show that the timing for the event in the mountains of North Wales was similar to that elsewhere in Britain and Europe. The occurrence of a pre-Allerød interstadial, almost certainly equivalent to the Bølling (conventional pollen zone Ib), is confirmed. Other sequences for the same period from lowland North Wales and elsewhere in Western Britain differ from the Nant Ffrancon sequence in that evidence for cooling between the Bølling and Allerød is missing, but some sequences from inland mountainous areas, or in Eastern Britain and the Continent are very similar to the Nant Ffrancon sequence.