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

A Scheduled Monument in St. Mary's, Isles of Scilly

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Latitude: 49.936 / 49°56'9"N

Longitude: -6.2954 / 6°17'43"W

OS Eastings: 91891.561762

OS Northings: 12826.11816

OS Grid: SV918128

Mapcode National: GBR BXVV.F73

Mapcode Global: VGYBY.TVRY

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

Scheduled Date: 16 November 1998

Source: Historic England

Source ID: 1013272

English Heritage Legacy ID: 15401

County: Isles of Scilly

Civil Parish: St. Mary's

Traditional County: Cornwall

Lieutenancy Area (Ceremonial County): Cornwall

Church of England Parish: Isles of Scilly

Church of England Diocese: Truro


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
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.

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.

Source: Historic England

Reasons for Scheduling

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'
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.

Source: Historic England


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

Title: 1:2500 Ordnance Survey Maps; SV 9112 & SV 9212
Source Date: 1980

Title: 1:25000 Ordnance Survey Maps; Isles of Scilly; Outdoor Leisure Series, No. 25
Source Date: 1992

Source: Historic England

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