The maritime character of Atlantic Europe gains increased prominence in the case of Britain and Ireland. These are not only islands themselves but Britain in particular is fringed by smaller islands, notably to the north and north-west, which contain some of the best-known Neolithic monuments. The postglacial colonisation of these island groups demonstrates the importance of maritime contact in the Early Holocene, and polished stone axe distributions reveal particularly close Neolithic contacts across the Irish Sea, with numerous British finds of Irish porcellanite axes balanced by Great Langdale axes in Ireland (Cooney 2000, 204). Cultural contacts beyond artefact exchange are illustrated by the Irish-style passage-grave art at Bryn Celli Ddu and Barclodiad y Gawres on Anglesey, at Calderstones near Liverpool, and at Pierowall Quarry on Orkney (Shee Twohig 1981). Connections across the Channel with northern France, on the other hand, appear less pronounced. Only a handful of dolerite axes from Plussulien in Brittany have been found in southern Britain, in contrast to the thousands of examples in north-west France. Parallels between the megalithic art of Ireland and Brittany have been proposed but are difficult to evaluate (Le Roux 1992; O’Sullivan 1997). The apparently late colonisation of the Isles of Scilly may also suggest that direct sailing across the western end of the Channel was too hazardous with the seacraft available to have been regularly undertaken.