Historical Context

Knepp Mill Pond is a man-made feature, created by the formation of a clay dam, or bay, across a shallow stream valley. It was created in connection with the iron industry as a means of developing a head of water to drive a waterwheel, either powering a set of bellows to fire a furnace, or a hammer to crush iron ore. Other mills may later have taken advantage of this power supply to drive corn-milling machinery.

Knepp Castle, etched by Charles Smith from a drawing by Lady Burrell, dated 1830

The date of its formation is not clear. In 1780 Sir William Burrell (2nd Bt) put forward the theory that the name of the original Castle may have been derived from the French expression ‘Nape d’eau’ meaning ‘sheet of water with the form of a table cloth’. This theory relies on the pond being in existence prior to the construction of the castle late in the 11th century. It could, therefore, be a remnant of very ancient iron workings.

A record in 1326 makes reference to a water mill at Knepp, which might indicate the existence of the pond. Records from the 16th century stating that the Caryll family were working iron at Knepp on behalf of the Duke of Norfolk in 1568, provide the first definite indication of its' existence.

Knepp had an important strategic location with good communications for that period. Proximity to north-south and east-west routes through the county were rare. Furthermore, 300 yards to the south of the former furnace site, (now known as Floodgates Farm), are the uppermost reaches of the canalised section of the River Adur. This represents another important transport link allowing timber and iron to be transported between Knepp and the coastal port at Shoreham.

The furnace at Knepp ceased operation in 1604; which is some time before the general decline of the Iron Industry of the Weald which occurred in the mid 17th century. One reason for this may have been that despite its enormous size, because of the small catchment area of the pond and its generally flat nature, there was insufficient water flow to drive the furnace bellows effectively.

The pond is shown on the Crow survey plan prepared in 1754, covering an area of nearly 80 acres. The figure below shows that the size of the lake has been steadily diminishing from that time, until the present day when only 28.87 acres of open water remain. The longest dimension of open water is now only 1000m, compared to 1400m in 1875, 1600m in 1847 and 1950m in 1754. The reasons for this may be twofold. Firstly, documentary and field evidence indicates that, historically, the level of the water in the pond was considerably higher than its present level . Any lowering of the water level will, therefore, have resulted in a corresponding reduction in surface area. Secondly, it is clear that there has been an enormous amount of silt deposition across the whole area of the lake, but especially at the northern end where the feeder stream enters, resulting in a shrinking back of the open water and reversion to dry land.

Nevertheless, in 1809 when John Nash was commissioned by Sir Charles Burrell to design and build the house at Knepp, the pond would have been the most prominent feature of the park. Nash’s design took advantage of the topography and the long views down this spectacular expanse of water. The new castellated mansion was sited so that in the views from it, the water would appear to be a part of the grand sweep of a river. An important part of the illusion was that the ends of the pond were not visible from the castle, in order to trick the viewer into thinking that the river continued on, as it curved away out of sight.

In the 200 years since the castle was built as the size of the lake has shrunk so this illusion has become less and less convincing. The headwaters, which have become silted up and overgrown with trees, are now clearly visible from the castle, and effectively block the long view that once extended northwards across the open water. Furthermore, the view south eastwards, towards the old ruin, is now almost totally blocked by trees and scrub that has grown up on the silted-up eastern arm of the pond near to Floodgates Farm. If one contrasts the views today with those depicted by Lady Burrell and H.S. Symms in the early 19th century (figure 17), it becomes very clear that that the loss of the lake has had a very detrimental effect on the setting that Nash originally intended for the castle.

Watercolours of the park by Lady Burrell c.1820

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