 Though it had been present in Great Britain before the last Ice Age, it did not recolonise afterwards and the ecology of the island grew up without it.Its presence today is due to humans introducing it, and it easily naturalises and becomes a pest in some situations, often covering whole hillsides (especially in Snowdonia and the western British Isles).In the British Isles, it colonises moorlands, uplands, shady woodlands (alongside escaped laurels and the native holly) and in areas of acid soils, often in shaded areas.