Lacking well-dated fifth millennium Mesolithic evidence and based on a consensus that late Mesolithic Britain was isolated from the continent, discussion of the Mesolithic–Neolithic transition has focused on the centuries around 4000 BC. This discourse has over-simplified complex neolithisation processes. New, high-quality evidence from 460,000 lithics found at Bexhill, Sussex, SE England, helps to redress this. Here, well-dated Mesolithic microliths (5500–4300 BC) may demonstrate continental links with neolithised communities. Alongside other sites, this offers exciting opportunities to contribute to debates on an isolated late Mesolithic during the transition. As a result, this work also provides additional explanations of new evidence proposing European influences on British Neolithic DNA. Instead of an isolated island, with this lithic evidence, we propose that the late Mesolithic Britain was culturally connected to the neolithised continent in the fifth millennium. Therefore, the Mesolithic–Neolithic transition of Britain was a longer, more complex, and nuanced process than previously thought.