Following the demolition of the mill, the Coultershaw Beam Pump was restored to working order and is now a scheduled monument, which is open to the public on summer weekends.

[7] Following the Dissolution of the Monasteries in 1536, the priory and its possessions were granted by charter by King Heny VIII to Sir William FitzWilliam, 1st Earl of Southampton.

[15] Correspondence relating to the tenancy of Coultershaw Mill by the Gwillim family from 1905 to 1930 is held in the West Sussex Record Office,[16] as is a copy of the final lease drawn up in August 1968 between "John Edward Reginald, Baron Egremont, of Petworth House" and "J. Gwillim Limited, Coultershaw"; this was for a period of twenty years at an initial rent of £1,250 per annum.

[15][20][21] Following the death of John Gwillim in 1972, the mill ceased to operate and the building was demolished the following year,[4] although the beam pump and water wheel were saved for restoration.

The main pipe led to a stone reservoir on the north side of the churchyard with branches to points in the lower levels of the town.

By 1575, the pipes were severely decayed and to help pay for their maintenance, Henry, 8th Earl of Northumberland endowed the town with the 7 acres (2.8 ha) Conduit Field, east of Hungers Lane on the south side of the road to Midhurst.

[25] By this time, the revenue from the lands at the Conduit Field were insufficient to finance the maintenance of the pipes and agreement was reached between the townspeople and the earl that, in return for receiving back the Conduit Field, he would carry out the necessary repairs and be responsible for the ongoing upkeep of the pipes with two wardens being chosen, one by the Earl and one by the town, who would supervise the maintenance of the supply.

[26] The pump was driven by an undershot wooden wheel and forced the water along a main pipe of 3 in (76 mm) inside bore to feed two reservoirs, one in Petworth Park, on Lawn Hill and the other in the south-east corner of the town to the west of Percy Row near the old gaol.

In 1839, it was recorded that the pipes from Coultershaw supplied 7 public and 146 private stopcocks in Petworth, including the brewery, malt house, a windmill and the Swan Inn.

Although there was still a plentiful supply of clean drinking water from the 17th century system, its distribution around the town was inadequate with only a small number of cisterns.

As a result, the inhabitants of the town found it more convenient to obtain water from the river system rather than make the long walk to and from the conduits.

Dr Kelly recommended that a new system should be installed to obtain fresh water from three springs in the neighbourhood and that sewage should be prevented from entering the river to avoid the risk of cholera or typhoid.

[27] Although Dr Kelly's proposals were not immediately acted upon, in 1882 agreement was reached between Lord Leconfield and the Rural Sanitary Authority that a new water supply should be obtained from springs at Gorehill to the south-east of the town.

Mason & Weyman steam engine with a Cornish boiler,[24] through 5 in (127 mm) pipes to a new reservoir near the Cottage Hospital, on high ground a mile east of the town.

[31] By the end of July 1792, the excavations had been completed to Coultershaw Wharf,[32] where the canal made use of the millstream, which here ran nearly due south, with the main stream of the river running in a large meander to the west with a weir at its head.

[34] In November 1794, the first barge loads of chalk arrived at the newly built kiln at Coultershaw,[35] which was situated to the east of the road about a hundred yards north of the mill.

[33] Until 1800, the turnpike from Chichester to Petworth descended Duncton Hill before crossing the River Rother at Rotherbridge, half a mile north-west of Coultershaw.

[37] Although Coultershaw was about 1.5 mi (2.4 km) south of Petworth, it was the nearest wharf on the navigation and quickly eased the transport of fertiliser, coal and building materials to the town and surrounding areas and improved access to wider markets for agricultural, timber and other products.

[49] The pump was operated by a breastshot water wheel which was direct coupled to a three-throw crankshaft (cast in 1912)[50] which swung three 12 ft 6 in (3.8 m) long beams pivoted at one end through connecting rods.

[54][55] Although the mill was demolished in 1973, the beam pump and water wheel were saved for restoration,[12] although the sluices and waterwheel paddles needed replacement.

[53] In 1976, the Sussex Industrial Archaeology Society received permission from the present Lord Egremont to restore the pump to working order.

The restoration was undertaken voluntarily by the society members in order to eventually open the site to the public[53] and was financed by grants from the Historic Buildings Section of the Inspectorate of Ancient Monuments,[51] West Sussex County Council and the Department of the Environment[56] as well as assistance from Lord Egremont, the owner of the land surrounding the installation.

[63] In July 2012, Lord Egremont officially "switched on" the Archimedes' screw water turbine which had been installed into the wheel pit of the former corn mill.

In July 2013, work was completed on a new boardwalk and footbridge spanning the river and former navigation, thus extending the site area accessible to visitors.