Kerbed platform cairn and prehistoric house platform 370m NNW of the Pest House, St Helen's


Heritage Category:
Scheduled Monument
List Entry Number:
Date first listed:


Ordnance survey map of Kerbed platform cairn and prehistoric house platform 370m NNW of the Pest House, St Helen's
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The building or site itself may lie within the boundary of more than one authority.

Isles of Scilly (Unitary Authority)
National Grid Reference:
SV 89916 17194

Reasons for Designation

The Isles of Scilly, the westernmost of the granite masses of south west England, contain a remarkable abundance and variety of archaeological remains from over 4000 years of human activity. The remote physical setting of the islands, over 40km beyond the mainland in the approaches to the English Channel, has lent a distinctive character to those remains, producing many unusual features important for our broader understanding of the social development of early communities. Throughout the human occupation there has been a gradual submergence of the islands' land area, providing a stimulus to change in the environment and its exploitation. This process has produced evidence for responses to such change against an independent time-scale, promoting integrated studies of archaeological, environmental and linguistic aspects of the islands' settlement. The islands' archaeological remains demonstrate clearly the gradually expanding size and range of contacts of their communities. By the post- medieval period (from AD 1540), the islands occupied a nationally strategic location, resulting in an important concentration of defensive works reflecting the development of fortification methods and technology from the mid 16th to the 20th centuries. An important and unusual range of post- medieval monuments also reflects the islands' position as a formidable hazard for the nation's shipping in the western approaches. The exceptional preservation of the archaeological remains on the islands has long been recognised, producing an unusually full and detailed body of documentation, including several recent surveys.

Platform cairns are funerary monuments of Early Bronze Age date (c.2000 - 1600 BC). They were constructed as low flat-topped mounds of stone rubble, up to 40m in external diameter though usually considerably smaller, covering single or multiple burials. Some examples have other features, including peripheral banks and internal mounds constructed on the platform. A kerb of slabs or edge-set stones sometimes bounds the edge of the platform, and a peripheral bank or mound if present. Platform cairns can occur as isolated monuments, in small groups or in cairn cemeteries. Current evidence indicates that nationally, but excluding Scilly, there are under 250 known examples of this monument class. On the Isles of Scilly, platform cairns form one of the recurrent types of small cairn represented in cairn cemeteries - an unusual and distinctive expression of this monument class, which forms a high proportion of the 387 surviving cairns recorded on the islands. By contrast, house platforms are one of several known types of settlement site dating from the Neolithic to the early medieval periods (from c.4000 BC to c.AD 1000). Individual house platforms may be dated by excavation or by their association with other monuments of known date. They consist of levelled stances, variously circular, ovoid or sub-rectangular in shape, on which similarly varied shapes of building were constructed. This broadly defined class of monument exhibits considerable variety of form nationally, largely depending on the nature and context of the buildings they supported and whether the platform was wholly or only partly occupied by the floor of the building. On the Isles of Scilly, house platforms tend to survive as rounded or oval levelled stances cut into hillslopes or into the scarps of field terraces. The stances are often provided with a bank or wall along the outer lip of the platform, thereby creating a hut circle built in an economical manner by using the levelling backscarp as a major part of the wall. Indeed a gradation can be drawn on Scilly from non-freestanding house platforms to fully freestanding hut circles. Excavations have confirmed the dating of house platforms on Scilly from at least the Bronze Age to the early medieval period, concurrent with more conventionally-built hut circles of round and ovoid forms on the islands. House platforms on Scilly may occur singly or in groups, unenclosed in the open or intimately associated with broadly contemporary field systems. House platforms form a significant proportion of the 140 hut circles and related forms of settlement site recorded on Scilly and by their nature they form the normal expression of prehistoric to early medieval settlement in steeper slope locations. The platform cairn and house platform in this monument have survived well and neither has been excavated. The close proximity of these respective funerary and settlement elements emphasises the varied uses which this exposed terrain has served from the prehistoric to medieval period, while the physical relationship between the cairn and the nearby prehistoric field systems typifies the organisation of land use during the Bronze Age.


The monument includes a prehistoric kerbed platform cairn and a nearby habitation site, called a house platform, situated on the north western coastal slope of St Helen's, an uninhabited island in the north of the Isles of Scilly. The cairn and the house platform are situated 20m apart on a north-south axis. The southernmost of the two, the cairn, survives with a circular mound of heaped rubble, 5.5m in diameter and up to 0.25m high on the north west side. The mound rises to a flattened platform, 4m in diameter and tilted slightly to the west in conformity with the surrounding slope. The platform perimeter is defined by a kerb of at least seven spaced slabs, most of which lie flat but they include two edge-set slabs: the largest on the west is 0.6m long and 0.3m high; the smaller slab, on the south, is 0.25m high. To the north of the cairn, the house platform is visible as a distinct ovoid hollow measuring 7m north east-south west by up to 6m north west-south east, cut into the fairly steep north west facing slope. The south eastern, rear, edge of the platform is cut 0.4m deep into the slope while a bank of similar height extends along the platform's north western edge. Beyond this monument, another kerbed platform cairn is located 35m to the east, while a further two similar cairns are located 110m to the SSE and a large round cairn containing a funerary cist is situated on the island's summit. Prehistoric field systems also occur on the island's lower western slopes and on the upper slope to the east of the summit. These broadly contemporary features are the subject of separate schedulings.

MAP EXTRACT The site of the monument is shown on the attached map extract. It includes a 2 metre boundary around the archaeological features, considered to be essential for the monument's support and preservation.


The contents of this record have been generated from a legacy data system.

Legacy System number:
Legacy System:


consulted 1988, Parkes, C/CAU, AM 107 for Scilly SMR entry PRN 7114, (1988)
consulted 1988, Parkes, C/CAU, AM 107 for Scilly SMR entry PRN 7266, (1988)
consulted 1988, Parkes, C/CAU, AM 107s for Scilly SMR entries PRN 7112-3, (1988)
consulted 1995, Parkes, C/CAU, AM 107 for Scilly SMR entry PRN 7114, (1988)
consulted 1995, Parkes, C/CAU, AM 107 for Scilly SMR entry PRN 7267.04, (1988)
consulted 1995, Parkes, C/CAU, AM 107s for Scilly SMR entries PRN 7112-3, (1988)
Title: 1:10000 Ordnance Survey Maps: SV 81 NE & SV 91 NW Source Date: 1980 Author: Publisher: Surveyor:


This monument is scheduled under the Ancient Monuments and Archaeological Areas Act 1979 as amended as it appears to the Secretary of State to be of national importance. This entry is a copy, the original is held by the Department for Digital, Culture, Media and Sport.

End of official listing

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