The island of St. Martin’s is home to one of the most populated tombs in British prehistory, containing the remains of up to sixty people. During the Bronze Age people were buried in entrance graves: roughly circular structures made of stones and soil that overlay a rectangular-shaped chamber and were surrounded by a kerb of boulders. It was possible to enter the chamber from outside and people were placed in these tombs over a period of years. Tombs of this type are confined to the Isles of Scilly and a small area of the mainland in West Penwith, Cornwall, Tramore, Ireland and small numbers of similar monuments are known in the Channel Islands and Brittany.
A programme of archaeological investigation at Knackboy Cairn started in 2006, this will continue in the 2007 season.