The Great Barn, Harmondsworth


Heritage Category:
Listed Building
List Entry Number:
Date first listed:
Date of most recent amendment:
Statutory Address:
The Great Barn, Manor Court, High Street, Harmondsworth


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Statutory Address:
The Great Barn, Manor Court, High Street, Harmondsworth

The building or site itself may lie within the boundary of more than one authority.

Greater London Authority
Hillingdon (London Borough)
Non Civil Parish
National Grid Reference:


Barn. Built in 1426-7 and substantially of that date. Later work of various periods including restoration by Peter McCurdy & Co. in 1987.

Reasons for Designation

The Great Barn, Harmondsworth, is listed at Grade I for the following principal reasons:

* Architectural interest: an outstanding and remarkably intact example of medieval carpentry, incorporating some innovative structural detailing. Its immense size makes it amongst the largest medieval barns known to have been built in England, and the largest to survive intact;

* Historic interest: it illustrates the pride and status of a great medieval institution, Winchester College, and commemorates the ambitions of its eminent founder, William of Wykeham;

* Rarity: in a national context it is of considerable rarity; in a regional context it is an exceptional survival;

* Documentation: the wealth of surviving documentary material relating to its construction and use is remarkable;

* Group value and setting: it has strong group value with the Church of St Mary, of Norman origins, and Manor Farmhouse, the successor to the medieval manor house, in what is still essentially a village setting.


The manor of Harmondsworth held by Harold Godwinson (prior to the Conquest) was granted by William the Conqueror to the Benedictine Abbey of Ste Catherine at Rouen in 1069. Such grants were not unusual, as in the first century after the Conquest many landowners enriched the monasteries of their homelands with English property. By 1086 the abbey seems to have placed a monk at Harmondsworth called Hertaldus or Hertaud, probably to manage the property and return surplus revenue to France: by 1211 his successor was being styled Prior, as were his fourteen known successors. As a foreign dependency, from the early C13 it was classed as an ‘alien’ priory (prioratus alienigae). Within this category it was one of about a hundred that rarely had more than two monks, had buildings more like manor houses than monasteries and no regular conventual life in the usual sense. After 1294 Anglo-French hostilities became so frequent, and government restrictions on residence and the movement of currency so severe, that these properties became increasingly useless to the parent houses. By the second half of the C14 they were correspondingly willing to part with them, a fact which attracted the attention of William of Wykeham, who from the early 1370s was assembling endowments for his planned foundations at Oxford and Winchester. Wykeham lighted on Ste Catherine’s property, and after a protracted process involving royal and papal permissions, purchased Harmondsworth in 1391 as part of the endowment of Winchester College.

The College installed a bailiff to run the estate, lodging him in the former Prior’s house, and made a number of repairs to the buildings, including, after a storm in 1397, to a tiled and timber-framed ‘corn barn’ and to the roof of a thatched ‘great barn’. By the mid 1420s, however, one of these barns - probably the ‘great barn’ - was deemed to be beyond repair, or possibly of insufficient capacity: either way, the College’s accounts record that in the period September 1424 to September 1425, a certain William Kyppyng, carpenter (carpentarius) was sent to view standing timber near Kingston-on-Thames ‘for the barn at Harmondsworth’, and the accounts for 1426-7 record the expenses for finishing it. Dendochronological analysis carried out in 1990 and in 2012 confirms that the existing building is the one mentioned in the accounts. The accounts refer in detail to ironwork supplied by John Derfford, smith, and name the tiler, Robert Helyer. Evidence suggests that the new barn was built a little to the west of its predecessor.

The barn’s purpose was the storage of the cereal crop harvested from the demesne, ie the 240 acres or so that the College farmed directly; tithe produce was kept, as later evidence shows, in a separate and smaller building, so that in common with all very large barns, the Great Barn at Harmondsworth was not a tithe barn. The crops of wheat, barley, oats and occasionally peas, were stored ‘in the ear’, ie in sheaves, carefully stacked in every available space except opposite the main doors; during the winter months the sheaves were threshed in the barn, inside the doorways. The separated grain was then stored in a nearby granary. Contemporary accounts preserved at Winchester College reveal a good deal about the personnel involved in using the barn, such as the Granger or barn-keeper (grangiator), the granary-keeper (granetarius) and their duties, and the complex procedures of filling the building and processing and accounting for its contents. The former Prior’s house (subsequently manor house) appears to have been rebuilt c1485-6.

In 1543 Henry VIII acquired Harmondsworth in exchange for several scattered ex-monastic properties, and on the accession of Edward VI in 1547 the estate was granted to Sir William Paget, who had been one of Henry VIII's leading advisers. Thenceforth, until the freehold was split up in the C19, the manor was usually divided into three or four farms under a variety of tenancy agreements, the largest of which, complete with the manor house, was called the ‘Court Lodge’. The Great Barn, too large for any single tenant, was shared by several or all of them, each with an allotted number of bays, an arrangement that helped the building avoid demolition or reduction in size, the fate of many great barns following the break-up of the great monastic or ecclesiastical estates they were built to serve. The manor house, which stood to the SW of the present farmhouse, was demolished in the 1820s when the latter was built.

In the C19 and early C20 the Great Barn attracted the attention of a number of important antiquaries and inspired a number of architects. In 1847 George Gilbert Scott (1811-78) made sketches there, later using them as the basis of two abortive schemes for Christchurch Cathedral, New Zealand; Basil Champneys (1842-1935) built the library at Mansfield College, Oxford (1887-9) with the barn very much in mind; Ernest Gimson (1864-1919), who had visited Harmondsworth with William Lethaby in the 1880s, clearly owed it a debt in designing his Memorial Library at Bedales School, Hants (1922). The building was much admired by Nikolaus Pevsner and by John Betjeman.

The barn remained in farm use until the late 1970s, but by then the character of the area had radically changed, largely due to the ever-more oppressive proximity of Heathrow Airport. It was substantially repaired in 1987, but by 2006 its condition and circumstances were worsening. In 2011, the building was purchased by English Heritage as the only viable way of securing its future.


Barn. Built in 1426-7 and substantially of that date. Later work of various periods including restoration by Peter McCurdy & Co. in 1987.

MATERIALS: oak frame and exterior cladding; some modern softwood pieces. Clay tile roof with tiles of many periods. Aisle posts standing on blocks of Reigate stone. Sill walls of ferricrete (a local iron-rich conglomerate), flint, brick, with some Reigate stone. Abundant post-medieval ironwork of many periods.

PLAN: oriented almost due north-south, the building measures 58.5 m (192ft) x 11.4m (37.5ft) and consists of a broad central nave, flanked by an aisle on each side, articulated transversely into 12 equal bays.

EXTERIOR: low sill walls, largely built of ferricrete, a late use of this material and in unusually large blocks, interspersed and galleted in flint. The dressings (quoins and door-jambs) were originally of Reigate stone, since largely replaced in brick of many periods. The barn’s three doorways, none of which ever had a porch, all face east; on the western side seven openings with single or double planked shutters, all above sill-beam level, have been inserted at various periods. The western and eastern walls were originally covered with vertical oak boards, fitted to rebates in the sill beam, wall-plate and main wall posts; about 80% of the boarding remains, an exceptional survival rivalled perhaps only by the Kentish barns at Littlebourne (1307-27) and Frindsbury (1404). The north gable wall covering dates substantially from 1987 as does the south wall, the original having been fire-damaged in 1972.

INTERIOR: the main structure consists of large square-sectioned arcade posts with thickened jowled heads jointed to both arcade plate and tie-beam. The arcade posts are braced to the tie-beams by large slightly concave braces, with similar braces to the arcade plates. The main roof is a simple principal rafter with collar and crown-strut, and a butt purlin with windbraces but no ridgepiece. The aisles have ties which interrupt the wall plates and have a raking strut which engages with the principal rafter and clasps a single purlin for the aisle. The aisle trusses are braced by a pair of braces meeting under the aisle ties, and each truss has a sill beam which engages with the aisle walls at one end and support the arcade plate at the other. The wall framing to the aisles consists of a centre stud and middle rail, resting on a high sill beam. The ends of the barn similarly have a centre post, a heavy middle rail set just above the aisle ties with subsidiary rails above and below. The half-hipped ends of the roof are supported by an arch-braced, intermediate, principal rafter collar truss, which receives the end of the purlins and supports the hip-rafters in mid-span. There is a small gablet above each hip.

The carpentry is interesting for a number of structural oddities, in particular:

1. The butt-purlin joints to the principal rafter over the nave are formed of diminished haunch tenons arranged upside-down; although an inept arrangement, this is at the same time a very early use of the diminished haunch tenon;

2. The roof structure includes crown struts – both precocious and outside their normal geographical range;

3. The aisle purlin is clasped by a raking strut, which is itself an early example, most dating from the C16;

4. The aisle wall plates are tenoned into the sides of the aisle ties – perhaps the earliest such arrangement in Britain – but an odd one to use here, as this lacks longitudinal strength.

The framing also shows evidence of some changes of plan during construction, resulting from the failure of the door-positions in the timber-framing, as first set out (probably off-site), to match the positions of two of the doorways anticipated by the builders of the masonry sill-wall. In bays 8 and 11 (counting from the south), the sill-beam and mid-rail have been pieced in, while the empty mortices in the underside of the wall-plate were clearly intended to house the door posts, clearly identifying these bays as the intended doorway positions. As completed, the doorways were placed in bays 7 and 10.

The building also has a notable range of apotropaic marks - symbols to ward off evil and bad luck - and an almost complete sequence of carpenters’ assembly marks and other graffiti.


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

Legacy System number:
Legacy System:


Books and journals
Victoria County History, , A History of the County of Middlesex: Vol 4, (1971)
Impey, E and Miles, D, The Great Barn at Harmondsworth ,


This building is listed under the Planning (Listed Buildings and Conservation Areas) Act 1990 as amended for its special architectural or historic interest.

End of official listing

Images of England

Images of England was a photographic record of every listed building in England, created as a snap shot of listed buildings at the turn of the millennium. These photographs of the exterior of listed buildings were taken by volunteers between 1999 and 2008. The project was supported by the Heritage Lottery Fund.

Date: 17 Dec 2001
Reference: IOE01/06218/15
Rights: Copyright IoE Mr Adam Watson. Source Historic England Archive
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