Culham Lock – Thames Path Online Guide

The river originally passed close to Sutton Courtenay and under a large mill there. In 1667 occurs the first reference to a pound lock underneath this mill. This had a set of gates beneath the mill floor and included a wide pool at the back of the mill. Consequently, it required a very large volume of water to fill it and so incurred a heavy toll. There were complaints to the Thames Navigation Commission in 1772 that the floor of the mill was a great obstruction to navigation. Although it was privately owned, the Commission undertook some improvements in 1789, but complaints persisted on the grounds of inconvenience and high tolls.

In 1803, Zachary Allnutt of Henley was appointed as Surveyor to the second and third districts of the Thames, which stretched from Mapledurham to Staines. He replaced John Clarke, who died that year, and was the son of Henry Allnutt, who was clerk to the Thames Commission from 1771 to 1820. Before his appointment, he had carried out a number of surveys for the Commission, including one for a new lock at Culham in 1802, but the scale of the works were larger than any previously undertaken, and the plan was not implemented immediately. However, he made a further survey in 1809, and work began in June, on the longest cut ever made on the Thames. It was 1,400 yards (1,300 m) long, with a lock at the lower end, constructed with stone walls, and with a relatively large drop for the time of 7 feet (2.1 m). A stone bridge with a span of 20 feet (6.1 m) was built to carry a road across the cut, and the work took just over a year to complete. The total cost of the project was just under £9,000, which included the purchase of the land. The project was overseen by George Treacher, who was awarded £100 in recognition of his services, when it was completed. Part of the older towpath around the backwater fell into disuse after the lock was built.