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Worms – a new enemy for the Knights Templar
Just below the street, along an alley in a quiet English market town, is an extraordinary survival from the time of the Crusades – a small cave richly carved in saints, knights, warrior monks, crucifixion scenes and folkloric figures more than 700 years ago. But there is a new struggle to be recorded. Simon Barber reports on the ongoing battle to beat the worm of time
Chalk-eating worms are just one of the signs of the slow decay that is threatening a unique historic underground cavern – a treasurehouse of ancient religious and secular carvings, linked to the Knights Templar. It is one of Britain’s most precious yet least-known medieval sites.
The Royston Cave, a beehive-shaped chamber, extends some 30ft beneath the centre of the Hertfordshire town – tucked away beneath a betting shop. Hewn out of a 180ft thick seam of chalk, the extraordinary medieval survival was uncovered by accident in 1742 during building work. Inside, depictions of biblical scenes and portraits of Christian martyrs were found cut into the chalk walls.
The cave has a lower, cylindrical portion, measuring some 17ft by 10ft, and a raised platform, with the cave’s total height measuring 25ft. Set in the roof is a small ventilation opening. The shape of the cave is thought to be modelled on the Church of the Holy Sepulchre in Jerusalem.
“The images are low relief carvings of medieval appearance, most of which were originally coloured,” says James Robinson, custodian of the cave. “Some scholars believe many of the carvings depict characters revered by the Knights Templar – warrior monks who protected pilgrims on their journeys to the Holy Land in the 12th and 13th Centuries.”
Notable is the description of St Katherine, for whom the Templars had a special reverence as it was on that saint’s day, 25th November 1177, that the knights won a victory over the Saracen leader, Saladin.
Other carvings include Saints Christopher and George, and a Sheela Na Gig figure – believed to have originated as a Romano- British fertility symbol.
Although the cave’s origins and purpose remain a mystery, there is no doubt about the importance of the Grade I listed site for British history. The only other known European example of a similar cave is at Sloup, in the Czech Republic.
“People are astounded that such a fascinating and mysterious site can exist in such an ordinary setting as the high street of small town.” says Robinson. “Beneath the modern façade of Ladbrokes’ betting shop and the main road lies a unique document of this country’s history.” But the survival of the cave now demands urgent action.
Over the past five years, an infestation of worms has began to attack the carvings, destroying some details and leaving a honeycomb appearance on localised areas of the walls. The porous nature of chalk makes it prone to soaking up moisture. Flooding and old sewage leaks have leeched into the walls, softening the chalk and providing nourishment for the worms, which feed on decayed matter and excrete the chalk.
Tobit Curteis, a specialist in the conservation of wall paintings and the control of the environmental causes of deterioration, has spent 18 months studying the cave. He has established that the decay, though very slow, is chronic and widespread.
“The problems at the Royston cave are very complex,” he says. “I’ve worked at historic sites all over the world, and this is one of the most complex situations I’ve encountered. It’s a unique place with unique issues. One has to accept that there will always be deterioration at sites such as this, but the current rate of decay is unacceptable. In some areas small sections of the chalk surface have been consumed and the detail lost. In other areas the effect has been to destroy the cohesion of the area of the chalk so it could collapse.”
Two types of worm have been found at the site – the larger of them, 20mm, has been preliminarily identified as Purple Brandling worm (Eisenia foetida); another transparent worm, 8mm, has yet to be identified.
A conventional remedy, such as the use of a biocide, is thought to be too problematic, as it may enter the water table or damage the remaining chalk. Filling the cave with carbon dioxide is not an option, due to the proximity the busy town, just a few feet away.
However, Curteis explains that the worms are peripheral issue and that the real problem of decay is caused by fluctuating moisture levels in the chalk, both from damaged pipes and water vapour. He also explains that there has not been an opportunity to take an holistic approach to the problem in the past, due to lack of funding.
“The history of conservation is paved with cases of people rushing in and covering things up with the latest new material which doesn’t tackle the underlying source of the problem,” he says.
Conservation work at the cave is funded by English Heritage via Royston Town Council – which owns the cave – and the cave is managed by the Friends of Royston Cave. Curteis’s work is the first long-term study of the site, and will go through further diagnostic stages before any treatment begins.
The main challenge with the structure and its artworks lies in the unusual material of its construction. The carvings were created within a band of Upper Cretaceous chalk, which is extremely soft and seldom found used for works of art. Consequently, there is scant research on how the material behaves under varying environmental conditions. The work at Royston is certainly breaking new ground.
“So far we have discovered that there are very fine vertical fissures opening up between the carvings and the bedrock.” says Curteis. “Once those holes start to expand the worms and microbiological organisms colonise them and exacerbate the damage. The big question is why are the fissures opening up in the first place?”
The movement is not drastic, perhaps a few microns a year, but eventually if a solution is not implemented the carvings will eventually fall from the walls and a unique treasure will be lost forever.
Royston Cave is in the town centre. The entrance is on Melbourn Street. It is open to the public during afternoons from Easter Saturday until the end of September. A small admission charge applies.