Civil War breastwork and two prehistoric stone hut circles at Little Porth, St Mary's


Heritage Category: Scheduled Monument

List Entry Number: 1013272

Date first listed: 16-Nov-1998


Ordnance survey map of Civil War breastwork and two prehistoric stone hut circles at Little Porth, St Mary's
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The building or site itself may lie within the boundary of more than one authority.

District: Isles of Scilly (Unitary Authority)

Parish: St. Mary's

National Grid Reference: SV 91881 12828, SV 91950 12791


Legacy Record - This information may be included in the List Entry Details.

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.

Civil War fieldworks on the Isles of Scilly are earthworks which were raised during military operations between 1642 and 1651 to provide temporary protection for infantry or to act as gun emplacements. The earthworks, which may have been reinforced with revetting or palisades, consist of earth and rubble platforms or banks and ditches. Three main types of Civil War fieldwork have been recognised on the Isles of Scilly: breastworks, batteries and platforms, which could be deployed separately or in combination to form a defensive complex. A breastwork is an earth-and-rubble bank, up to 4m wide and 1.7m high but generally much smaller, running beside the coastal cliff edge and usually accompanied by a ditch along its landward side. Sixteen surviving breastworks are recorded on the islands. A battery is a levelled area or platform, generally up to 20m across, situated on a hilltop or terraced into a slope to serve as a gun emplacement. They vary considerably in size and shape and are usually partially or wholly enclosed by a bank, occasionally incorporating one or two outer ditches. Twenty batteries survive on the Isles of Scilly, several connected by breastworks. Adjacent to some batteries are examples of the third fieldwork type, platforms. These are partly terraced into, and partly out from, sloping ground and represent sites of lookouts and temporary buildings. Eight such platforms, measuring up to 12m by 8m in size, are known to survive on the islands. The fieldworks were designed to defend the deep water approaches to the islands, especially St Mary's where most examples are found. Fieldworks are also known from Tresco, Bryher, Samson, St Agnes and Gugh. The circumstances of their construction are recorded in contemporary historical documents which indicate most were produced by the Royalist forces which controlled the islands for the entire Civil War period except during 1646-8. The Civil War fieldworks of the Isles of Scilly form a major part of the 150 surviving examples of fieldworks recorded nationally. They present an unusually complete system of fortifications from this period, both in the surviving range of fieldwork types represented and in the surviving pattern of their strategic disposition. By virtue of their sometimes extensive nature and coastal situation, the Civil War fieldworks on Scilly may overlie earlier remains that have become located and exposed on the coastal margin due to the gradual submergence of the land mass forming the islands. Such remains may include stone hut circles, the round houses of early inhabitants on the Isles of Scilly. Excavation has shown that hut circles were built on the islands from the Bronze Age to the early medieval period (c.2000 BC - AD 1066), though during the Romano-British period (AD 43 - AD 400) complex forms were developed with multiple rooms and annexes, classified separately as `courtyard houses'. Stone hut circles survive with rubble or earth-and rubble walls or banks defining circular or ovoid internal areas, usually levelled and ranging from 2.5m-13m across, though generally 3m-5m across. The walls may incorporate natural ground-fast boulders or outcrops and sometimes have a facing of edge-set slabs, large blocks or occasionally of coursed rubble walling along one or both faces. Some hut circle walls show entrance gaps, 0.5m-2m wide, sometimes flanked by end-set slabs or blocks. Remains of thatch or turf roofing are not preserved but excavations have revealed post- and stake-holes for roof supports and internal subdivisions. Excavation has also revealed a range of domestic artefacts and, in a small number of later examples, evidence for metal working. The deposits within and around hut circles may also include quantities of midden material. Stone hut circles may occur singly or in small or large groups, and either closely spaced or dispersed. At least 136 hut circles are recorded on the Isles of Scilly, widely distributed but biassed towards the lower land, the coastal margins and the inter-tidal zone, reflecting the subsequent submergence of much low-lying land that formed the original landscape context in which many such settlements were built. Hut circles may be associated with broadly contemporary field systems and funerary monuments, while some examples dating to the Romano-British and early medieval period are included within sites forming religious foci. They embody a major part of our evidence on the economy and lifestyle of the islands' past inhabitants. Their longevity of use and their relationships both with other monument types and with the islands' rising sea level provides valuable information on the developing settlement patterns, social organisation and farming practices throughout a considerable proportion of the islands' human occupation. The Civil War breastwork in this monument forms the northern part of an inter-related complex of Civil War fieldworks which has survived unusually well, despite some encroachment in places by the coastal cliff as is evident in the sector covered by this monument. The disposition of this breastwork, relative to the other fieldworks, and the survival of extensive documentation giving the historical context in which these defences were built, demonstrate clearly the strategic methods employed by the Civil War military forces and the function of fieldworks within those methods. This is emphasised by the situation of this series of complementary fieldworks, including this monument, flanking an important maritime approach. The prehistoric hut circles beneath and immediately beyond the north west end of the breastwork provide by far the nearest evidence for the settlement context for the important grouping of broadly contemporary entrance graves and the prehistoric field system on Innisidgen Hill. Although truncated by the cliff face, they form the eastern part of a spread of recorded prehistoric settlement sites and field systems in the inter-tidal zone and coastal margin of Little Porth and Bar Point which, with its accompanying environmental data, has allowed an unusually good view of the developing land uses in this low-lying part of the islands. The coastally exposed location of this evidence demonstrates well the effects of the islands' rising sea level on the settlement pattern and the resulting truncation of the archaeological record.


Legacy Record - This information may be included in the List Entry Details.


The monument includes a length of defensive bank and ditch, called a breastwork, dating to the English Civil War, which runs behind the coastal cliff of Little Porth on the north coast of St Mary's, Isles of Scilly. The breastwork in this monument forms the north western extent of an inter-related system of Civil War defensive fieldworks which survives along much of the north east coast of St Mary's. At the north western end of the monument, two prehistoric stone hut circles are exposed in the cliff section close to the north west end of the breastwork bank. The monument is divided into two separate areas by a 30m break where the breastwork's surviving length has been interrupted by a subsequent incursion of the coastal cliff. The Civil War breastwork survives as an earth and rubble bank, up to 2m wide and 0.7m high, with a ditch, up to 3.5m wide and 0.4m deep, along its landward side. The south east sector of the breastwork survives over 25m, extending north west from its original terminal behind a relatively high sector of the coastal cliff and descending to the lower cliff edge where its line has been truncated by recent coastal erosion. The erosion causes a gap 30m wide in the breastwork ditch and 45m wide in its bank. The breastwork reappears to the north west of the eroded gap and is visible over a further 70m to the north west, running immediately behind the coastal cliff which has eroded into the outer side of the breastwork bank in places. At the north west end of the monument the breastwork is again truncated by the coastal cliff. The two prehistoric hut circles are located 10m apart on a south east- north west axis. The south eastern hut circle is visible in the cliff face deposits beneath the north west surviving end of the breastwork bank. The hut circle has been truncated by the advancing cliff face such that only the south western arc of its inner wall face survives. Built of irregularly coursed slabs and rubble, it is visible over a length of 2m along the cliff face and is up to 0.5m high. The base of the hut circle wall is situated 1.5m above the present base of the cliff and is built on a dark sandy loam in which the walling is also embedded to the south east; adjacent to the north west of the walling, the silted deposits in the breastwork ditch cut enter the cliff section. The base of the wall is 0.2m above the upper limit of the orange natural subsoil with granite rubble, locally called `ram', which forms the lower 1.3m of the cliff section at this point. The upper edge of the wall extends along the top of the cliff edge. Ten metres along the cliff face to the north west, and beyond the surviving end of the breastwork, the other hut circle is visible both in the upper cliff section and in the surface of a hollow in the sand dunes behind the cliff. This hut circle also retains only the south west arc of its walling, together with some of the adjacent internal deposits within the arc. Its wall has an inner face of at least five spaced edge-set slabs, up to 0.5m long and 0.5m high, giving a surviving internal diameter of 2.5m; the nature of the wall's core is masked by dense surface vegetation on and behind the upper cliff section but previous observations have recorded a heaped rubble core, 0.5m wide. Where the wall's facing-slabs meet the cliff section, 1.75m high at this point, their bases are embedded in the dark sandy loam and show a similar relationship to the subsoil `ram' as described for the south eastern hut circle. The south east facing slab in the section has a smaller, vertical, packing slab, 0.25m high, against its inner face. The breastwork in this monument forms part of an integrated system of Civil War coastal defences which survives extensively around St Mary's and includes breastworks bordering potential landing places and near important settlements and installations, coupled with a system of batteries commanding complementary fields of fire over the waters around much of the island's coast. This breastwork provided cover against landing parties over a relatively low-lying portion of coastal cliff adjacent to Crow Sound, the principal approach for shipping from the east into the Isles of Scilly. This portion of breastwork supplemented a more extensive length of breastwork around the coastal edges of Innisidgen Hill and Helvear Down, from 70m south east of this monument. That breastwork incorporates three gun batteries and a blockhouse which themselves complemented the fields of fire of larger, more elevated batteries situated behind Bar Point, 85m south west of this monument, and on Helvear Hill, 500m to the south east. The prehistoric hut circles in this monument form the eastern part of a dispersed group of prehistoric settlement sites recorded in the inter-tidal zone and adjacent coastal exposures on the western side of Little Porth, together with traces of a broadly contemporary field system and evidence for later agricultural activity in the early medieval period. Inland from the coastal erosion zone along this northern edge of St Mary's, extensive sand dune formation has masked the land surfaces and any associated archaeological remains but sand extraction south of Bar Point has revealed a prehistoric regular field system from 165m WSW of this monument, with further hut circles exposed in the inter-tidal zone to the west. A similar field system is visible on the northern slopes of Innisidgen Hill, from 100m south east of this monument. Two broadly contemporary prehistoric funerary monuments, called entrance graves, are also located on Innisidgen Hill, 155m and 250m to the south east respectively, and a third funerary monument, a round cairn, is located 130m to the SSW on Helvear Down. Pollen analyses both from Innisidgen and the Bar Point field system have demonstrated the vegetational sequence accompanying these successive changes in land use and sea level.

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: 15401

Legacy System: RSM


Books and journals
O'Neil, BH St J, Ancient Monuments of the Isles of Scilly, (1960)
Dimbleby, G W, 'Cornish Studies' in A buried soil at Innisidgen, St Mary's, Isles of Scilly, , Vol. 4/5, (1977), 5-10
Evans, J G, 'Cornish Studies' in Excavations at Bar Point, St Mary's, Isles of Scilly, 1979-80, (1983), 7-32
Evans, J G, 'Cornish Studies' in Excavations at Bar Point, St Mary's, Isles of Scilly, 1979-80, (1983), 7-32
consulted 1994, Parkes, C/CAU, AM 107 for Scilly SMR entry PRN 7453.03, (1988)
consulted 1994, Parkes, C/CAU, AM 107 for Scilly SMR entry PRN 7471, (1988)
consulted 1994, Parkes, C/CAU, AM 107 for Scilly SMR entry PRN 7477, (1988)
consulted 1994, Parkes, C/CAU, AM 107 for Scilly SMR entry PRN 7477.02, (1988)
consulted 1994, Parkes, C/CAU, AM 107 for Scilly SMR entry PRN 7483, (1988)
consulted 1994, Parkes, C/CAU, AM 107 for Scilly SMR entry PRN 7486, (1988)
consulted 1994, Parkes, C/CAU, AM 107s for Scilly SMR entries PRN 7453.01-.02, (1988)
consulted 1994, Parkes, C/CAU, AM 107s for Scilly SMR entries PRN 7454-6; 7487, (1988)
consulted 1994, Parkes, C/CAU, AM 107s for Scilly SMR entries PRN 7476 & 7480, (1988)
Title: 1:2500 Ordnance Survey Map; SV 9112 Source Date: 1980 Author: Publisher: Surveyor:
Title: 1:2500 Ordnance Survey Maps; SV 9112 & SV 9212 Source Date: 1980 Author: Publisher: Surveyor:
Title: 1:25000 Ordnance Survey Maps; Isles of Scilly; Outdoor Leisure Series, No. 25 Source Date: 1992 Author: Publisher: Surveyor:

End of official listing