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Glastonbury Tor: conservation and site management

Published in the RICS Conservation Journal, Spring 2004

A programme of works by the National Trust to repair St. Michael’s church tower on Glastonbury Tor, and to carry out site improvements, has been underway since 2001.  The project has been funded by the Heritage Lottery Fund and the National Trust, including money raised by a public appeal.   In addition to being a necessary phase of conservation, repair and adaptation, the work has cast new light on the history of the tower and the site as a whole.  The unusual location has presented particular logistical challenges in carrying out the work.  

A previous church on the summit of Glastonbury Tor, dating from the Saxon period, was severely damaged in an earthquake in September 1275.   The rebuilt church, incorporating parts of the former church, is now believed to date from the fifteenth century.1 In its elevated position, the tower would have acted as a sound-beacon for the lands on the far side of the Tor from Glastonbury Abbey.   The church was abandoned following the closure of Glastonbury abbey in 1539 and the bells taken town.   As Jerry Sampson, the project archaeologist has obseverd, it seems that the tower was left as a warning to the people of Somerset of what becomes of traitors to the King.2

The north east corner of the tower, with its attached stair tower,  collapsed sometime in the following century, possibly as a result of a lightning strike.   Celia Feinnes, visiting in the 1690’s, noted: ‘...there is only a little tower remaines like a Beacon; it had Bells formerly in it, and some superstition observ'd there but now it’s broken down on one side.'3   A water colour from the  eighteenth century shows the structure on the point of total loss, although it also suggests that by this time the tower was seen as an object of interest, worthy of preservation.   The Tor was bought by Richard Colt Hoare of Stourhead in 1736, who subsequently funded the rebuilding of the collapsed corner and parts of the parapet.    The parapet was further altered in the nineteenth century.4

Glastonbury Tor was acquired by the National Trust in 1933.   Repairs to the tower, deferred by the Second World War, were carried out by Alves & Co of Glastonbury over the summers of 1948 and 1949.   The file in the Public Record Office reveals how  advice from the Ministry of Works in Bristol to use Somerset hydraulic lias lime was not passed on to the local builder, with the tower being repointed in Portland cement.    Not unrelated to this, the tower was designated as a Scheduled Ancient Monument in 1951.5  

The summit to the east of the tower was excavated under the direction of Philip Rahtz from 1964-66.   Rahtz found parallel fissures in the rock surface of the Tor containing archaeological remains,  suggesting ground movement either at the time of the 1275 earthquake or more recently.   Rahtz concluded: “…whether this process still continues, is not possible to say; but if it does, it must inevitably cause the ultimate collapse of the surviving tower of the church of St. Michael .”6

By the 1970’s wind erosion at the summit had lowered the ground level around the base of the tower, beginning to expose the footings, with the possibility of the foundations being undermined.   In response, a protective apron was put down, consisting of concrete setts on hardcore covered with a thin concrete topping.   The topping incorporated a “wire-tex” mesh to deter treasure hunters. 7   The railings surrounding the tower, dating from the early nineteenth century, were also removed at this time.

With increased visitor numbers from the 1960s onwards, erosion by man was also to become an issue.  The man-made terraces on the sides of the Tor, known as “strip lynchets” are a distinctive feature, the precise origin of which is still uncertain.8   Faced with a steep climb, visitors took the shallowest route, with pathways forming naturally along these lines.   By the 1980’s, in some areas, these pathways were cutting deep into the sides of the Tor.9  The concrete pathways and steps were laid down at this time, to protect the Tor from further erosion by footfalls.10

In 1999, a conservation plan for Glastonbury Tor was drawn up by the property manager, Adrian Woodhall.   A condition survey of the tower was carried out by the present writer in 1999, in association with rope access specialists Henry Chesher Stone Conservation.    The tower was found to be generally sound, with some damage caused by decaying wrought iron cramps,  and it was plainly suffering from cement pointing applied in the 1940’s.   The condition report also made recommendations for site improvements, and in particular improvements to site access – kissing gates, additional seats, handrails etc -  incorporating recommendations made by Valerie Wenham,   the National Trust’s disability advisor in 1998.     

Site improvement work was carried out in 2001.  A conscious decision was taken to improve site features and access in advance of the works to repair the tower itself.   Inevitably the steep hill would deter some.   However it was considered important that efforts should be made to encourage assist people to undertake the climb, in particular to see the repair work in progress when it began. 11

The question remained as to the condition of the ground beneath the tower itself, and the significance of the fissures that Rahtz had found during the 1964-66 excavations.   Engineering geologist Ted Wilson advised that the fissures were a permanent feature of the summit, formed during the last glacial period when ice sheets adjoined Somerset , and were not fragmentation as such.12   However, the possibility of voids forming with the fissures, for instance as a consequence of ground water movement, remained.  Of particular concern was a fissure to the east of the tower, not fully excavated by Rahtz, and potentially undermining the south east corner.    

GSB Prospection was engaged to resolve the uncertainty, carrying out magnetometry and ground radar surveys of the summit in June 2002.   Both techniques gave a consistent signal, suggesting that the fissures beneath the church had been compacted by the medieval builders, and that no voids had formed since.  It was decided therefore not to excavate to excavate to inspect the foundations.    

The repairs to the tower itself were carried out in the summer months of 2003 by St. Blaise Ltd, under the direction of site manager Ian Gangadeen.   The location of the tower on the top of a steep sided hill, 150 metres above the Somerset levels, presented particular logistical difficulties.   The 1948-49 repairs had made use of horses to drive a simple winch system.   By the 1970’s, when summit protection works were carried out, the Royal Navy had provided a Sea King helicopter from nearby RNAS Yeovilton.   In January 2003, a similar offer from the Joint Helicopter Command had to be withdrawn in the light of imminent military commitments in the Gulf.   Although this was a blow to the project, St. Blaise managed to locate a commercial helicopter and the lift went ahead in April.   After days of careful assembly and laying out, the ease and speed with which the helicopter lifted the materials and equipment to the summit was impressive.   A John Deere “Gator” utility vehicle, used on a daily basis by St. Blaise to bring materials to the summit, was also invaluable to the project.  

The logistical difficulties overcome, the works themselves were relatively straightforward.  Areas of the parapet which had moved due to a combination of corrosion of cast iron cramps or settlement of rubble walling were rebuilt.   One course of the parapet on the south side was reordered to improve the bonding with the courses above and below.    On the west facade, lengths of eroded string course, were repaired with Doulting stone, in order to better protect canopies and surviving statuary.  The repairs were camouflaged by St. Blaise’s conservators, to the dismay of the head mason, a former S.P.A.B. William Morris Craft Fellow.13

The most radical intervention into the masonry was to the rubble walling on the upper storey on the south side.   Here a combination of the highest exposure of any part of the tower, and the effects of the hard 1940’s pointing had caused large areas of stone to fracture.   The   stone originally used,  a limestone from the Upper Lias known as  “junction bed”,  was quarried about half a mile from the Tor itself. Consultant geologist Hugh Prudden advised using Hadspen stone from Castle Cary (also known as “Cary Stone”) as a suitable  commercially available replacement.  The Hadspen stone is slightly lighter than the junction bed stone, allowing the repaired areas to be distinguished from the medieval work.

The 1940’s exterior cement pointing came off quite easily from the rubble stone and was removed in its entirety.    Cement pointing only removed locally on the ashlar areas.   The repointing consisted of West Knighton sand from Dorset and Blue Lias hydraulic lime from the Tout Quarry at Charlton Adam, nearby.    The pointing on the rubble work was brought quite full to reduce surface area exposed to the elements and in increase evaporation through the joints.        The use of the Blue Lias hydraulic lime has given the tower a brighter, happier, appearance than previously.    The scar of the rebuilt north east corner is more apparent than before, and the history of the tower clearer.    In this context is was sad to hear during the works that Hydraulic Lias Limes Ltd had lost the public inquiry into its application to reopen the quarry at Appledoor in Somerset, with future supplies of the material now uncertain.

The close archaeological inspection carried out by Jerry Sampson during the works has furthered our understanding of the tower’s construction and history; in particular in relation to the earlier church, much of which is believed to have survived the 1275 earthquake   to be incorporated in the new church.    A close similarity between details on the tower and at the church of St Cuthbert in Wells suggests that the tower is fifteenth century, a hundred years later than previously supposed. 14   The visitor information plaque inside the tower was amended accordingly.   

Six brass target markers were fitted to the east and west facades of the tower to enable precise monitoring of future movement.   The concrete apron at the base of the tower protecting the footings will be renewed as part of the final phase of the project and further improvements to the site carried out.    The wide range of information generated by the project - reports, drawings, photographs etc - is now being collated, with the possibility of a publication about the Tor under consideration.  


Special thanks are due to the staff of St. Blaise Ltd, for making the job such an enjoyable one to work on: site manager Ian Gangadeen, site foreman Jamie Whiteman, conservators Fiona & Robin Gullen-Smith, head mason Gary Brookes and the rest of the team.  

Thanks are due to various current and former staff at the National Trust:   Tracey Hartley, who commissioned me to survey the tower in 1999;    Adrian Woodhall, the property manager and author of the site conservation plan;   Mark Perkin, who retained me as architect for the repair of the tower itself; Helen Brown who was project manager before and during the site phase of the tower repair works, and Martin Papworth, the regional archaeologist.   Cost advice was provided by Adrian Stenning and Claire Chandler of quantity surveyors Bare Leaning & Bare.   Structural advice was provided by Stuart Tappin of Faber Maunsell.   Ross Dallas advised on the procurement of photographic and photogrammetric surveys.  The project monitor for the Heritage Lottery Fund  was Kevin Heaton of the MDA group, advised on technical matters by Nicola Sterry of English Heritage.   Other contributors to the project are mentioned in the text.


1 Sampson, J.,   Glastonbury ; St Michael on the Tor, Archaeological survey, 2003. Unpublished at present.

2 Sampson, J., “For the record: St Michael’s Tower”, S.P.A.B News, Vol.24 No.4 2003, p6.

3 Sampson, Archaeological survey

4 Sampson, Archaeological survey

5 PRO file Works 14 1973

6 Rahtz, P., “Excavations of Glastonbury Tor, Somerset, 1964-66”, Archaeological Journal vol.127, 1970, pp 1-81.

7 Architect: Caroe & Partners.   Builders: Cribb & Son.

8 Research by Charles & Nancy Hollinrake for the National Trust Wessex Region. Unpublished at present.

9 Conversation with Donald Cribb of Cribb & Son, who built the paths in the 1980’s.

10 From the National Trust files, it can be seen that trials of various materials were carried out. Stone was rejected as being too slippery.

11 One recommendation not carried out was to make the lower slopes of Tor Field itself wheelchair accessible, so that wheelchair users could have a view of the tower and south over the Somerset Levels.  A feasibility study carried out in 2000 found that an entirely new path would be required from the upper site entrance, cutting diagonally across a field to Tor Field itself.   We concluded that the new path could not be justified in archaeological terms.

12 EJ Wilson & Associates.   Unpublished reports for the National Trust Wessex Region. Ted Wilson’s research also confirmed that the 1275 earthquake, was indeed an earthquake and not a landslip as has been supposed.   The Edinburgh Earthquake Centre confirmed that an earthquake on 11 th September 1275 , centred approximately where Portsmouth is today, caused widespread damage in southern England.

13 I have since learned from the architect Alan Thomas of Wells  that new Doulting stone does if fact tone down quite quickly.

14 Sampson, Archaeological survey.

Stukeley's view of


© Keith Garner Ltd 2011