The
Domesday Book, compiled in 1086 records a mill at Petworth, which almost certainly referred to the mill at Coultershaw. By the mid-13th century, the mill was owned by the
Percy family, and in July 1240, William de Percy endowed the priory at
Shulbrede near
Linchmere with the mill at "Cutersho" while retaining the right to "the free grinding of all kinds of corn which shall be used in his house at Pettewurth". He also granted the priory the right to take earth from his land near the mill to repair the mill-pool when necessary, and granted that the "
villeins" at
Tillington and Petworth should give the prior up to three days' aid each year to repair the mill-pool. In consideration for the transfer, the prior was to pay Percy or his heirs two marks of silver each year until such time as Percy gave "ten librates of land in a suitable place in Sussex or Yorkshire" to the prior, after which the mill would revert to Percy. The Percy family failed to exercise their right to reclaim ownership of the mill; in the Sussex Hundred Rolls of 1275, the mill was shown as belonging to the priory, with an annual value of £10. In 1291, in
Taxatio Ecclesiastica (a survey of temporal property held by religious bodies granted to
King Edward I by
Pope Nicholas IV), the mill (now valued at £2 per annum) was recorded as at "Catesstowe" or "Cotestoke" while in 1380 it was recorded as at "Codestowe". When the priory was surveyed for
Valor Ecclesiasticus (a survey of the finances of the church made in 1535 on the orders of
King Henry VIII), the mill (now at "Cowtershall") was still recorded among the priory's assets, with an annual value of 53s 4d. 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. The mill subsequently reverted to the Percy family.
Lady Elizabeth Percy inherited the Petworth properties on the death of her father in 1670. In 1682, she married
Charles Seymour, 6th Duke of Somerset, and so became Duchess of Somerset, with the Duke thus becoming the owner of the Petworth estate. In 1703 the court roll refers to a "mill called Coutershoal Mill" being kept up "for the conveniency and service of the tennants and that it is the custom of this manor for the tennants to grind at the said mill". The Duke of Somerset died in 1750, followed two years later by his son,
the 7th Duke. On the death of the 7th Duke, his nephew,
Charles Wyndham, inherited Petworth and the title
Earl of Egremont. There were two corn mills and a malt mill recorded on the site in 1534. The mill was destroyed by fire in 1923, and an unattractive steel-framed concrete building replaced it. From the early 20th century until the mill was closed in 1972, the mill was operated by the Gwillim family, who also operated North Mill in Midhurst. Correspondence relating to the tenancy of Coultershaw Mill by the Gwillim family from 1905 to 1930 is held in the West Sussex Record Office, 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. In 1930, John Gwillim and Novadel Limited registered a patent for "Improvements in plansifters and the like" (United Kingdom Patent GB353145). A "plansifter" was "a stack of sieves of decreasing mesh size that separate particles by size" for use in milling operations. In 1992, Phyllis Catt, the daughter of John Gwillim published ''"A Miller's Daughter"'' in which she recorded her experiences living at the mill and North Mill, Midhurst to a background of the "rumble of machinery and the rush of water". Following the death of John Gwillim in 1972, the mill ceased to operate and the building was demolished the following year, ==History of Petworth's water supply==