The Isles of Scilly form an archipelago some 27 miles (43 km) WSW of Land’s End, Cornwall, and lie within an oval area about 12 miles (19km) SW-NE and 5 miles (8km) NW-SE. Five islands (St Mary’s, Tresco, St Martin’s, Bryher and Agnes; Fig. I) are inhabited, most of the permanent population of 2,000-plus being on St Mary’s. Some 40 further smaller isles bear vegetation, several with signs of former occupation, and there are several hundred more descending to mere rocks and reefs. The total exposed land surface at HWNT is c. 3,900 acres (1,600 ha). Scilly is almost entirely granite, the lowlying area between the isles being mainly a fine, white, granite-derived sand. Scilly is also the most southerly detached landmass of Britain and is botanically just within the extreme northern range of various species (Lousley, 1971). The islands are constitutionally quite separate from Cornwall, with a divergent recent social history (best accounts: Matthews, 1960; Gill, 1975). and a separate, only partly Celtic, linguistic one (cf. Thomas, 1979b), relevant here where place-names can reflect physical development. The archaeology of Scilly, first brought to wider notice by Borlase (1756), has long centred around the inordinate number of post-neolithic entrance-grave cairns (Hencken, 1932; Daniel, 1950), and has only recently been accorded a full length study (Ashbee, 1974).