In the early 20th century, one of England’s most remarkable architectural rescue operations took place in conditions that would challenge even modern engineers. Winchester Cathedral, whose cornerstone was laid in 1079 and whose construction developed over several centuries, had begun suffering serious foundation problems by the beginning of the 1900s. The cathedral stood on ground containing peat and other unstable materials near the River Itchen, and centuries of changing groundwater levels had contributed to the deterioration of its timber foundations. By 1904, cracks had appeared in the building, raising fears that the enormous medieval structure could eventually collapse. The solution would require an extraordinary combination of engineering, construction and underwater diving—and a diver named William Walker would become central to the effort.
The fundamental problem was hidden beneath the cathedral. Parts of Winchester Cathedral’s foundations rested in ground affected by water, while the crypt beneath the nave was partly below the water table and could flood during periods of heavy rain. Over time, fluctuations in water levels contributed to the decay of wooden foundation materials and compression of the peat beneath the structure.
Engineers faced a difficult dilemma: removing groundwater through conventional pumping could cause the surrounding silt and unstable ground to shift, potentially making the cathedral’s settlement worse. Instead of fighting the water, engineers developed a radical strategy that would allow workers to reinforce the foundations while the ground remained submerged. Engineer Francis Fox was consulted, and the resulting plan called for trenches to be dug around the building and filled with cement. To carry out the dangerous work below the waterline, an experienced diver was needed.
William Walker answered the call for divers after the search began in 1905. Based in Portsmouth, Walker already had valuable experience as a shipyard diver, a profession that demanded technical skill and the ability to work in difficult underwater environments.
Beginning in 1906, he spent years beneath Winchester Cathedral in murky water and near-total darkness. Working roughly 20 feet below the surface, he entered narrow trenches that could be around six feet deep and manually cleared away deteriorated material so the cathedral’s foundations could be strengthened. Surface-supplied diving technology allowed Walker to breathe through an air hose connected to equipment above ground, but the technology did not make the work easy. Visibility was extremely poor, meaning much of his work had to be performed by touch.
The scale of the operation was enormous. Winchester Cathedral stretches approximately 558 feet, or 170 meters, in length and about 82 feet, or 25 meters, in width. Engineers ultimately created 235 pits around the cathedral’s perimeter, each extending approximately 20 feet, or six meters, downward. Walker’s task involved descending into these confined spaces, removing rotten timber and unstable peat, and continuing down toward the more stable gravel layer beneath the original foundations.
The work was painstaking because every movement had to be made carefully in conditions where the surrounding water and soil could not simply be treated like a conventional construction site. The fact that the cathedral remained standing while this extraordinary operation took place added another layer of risk to every stage of the project.
Once Walker cleared the deteriorated material, the reinforcement process could begin. He packed the bottoms of the underwater pits with jute bags filled with hydraulic cement. After the cement had hardened sufficiently, water could be pumped out of the reinforced trenches, creating conditions in which conventional masons could continue the construction work. Concrete block piers were then built upward from the stable gravel layer to provide new structural support for the cathedral.
The figures reveal just how labor-intensive the rescue was: by the end of the operation in 1911, Walker had placed approximately 25,800 bags of cement. Masons subsequently used about 114,900 concrete blocks to construct the new foundation supports, while approximately 900,000 bricks were used to repair parts of the cathedral above ground.
