Today it runs parallel with the M20 motorway for much of the first part of its journey: it passes between the hamlet of Fairbourne Heath and Harrietsham; after Broomfield, the river becomes the lake adjoining Leeds Castle.

[2] The river powered a number of watermills on itself and its tributaries in the parishes of Ulcombe, Leeds, Hollingbourne, Boxley and Maidstone.

The mill had collapsed by the time Coles Finch visited it and was demolished in 1929, although the waterwheel and pentrough by Weeks of Maidstone survive.

The previous owners were Thomas Hatche and Richard Austen, who had recently sold the mill at that date.

Seventeenth-century millers in Ulcombe include Willia Pettit (1612), Percival Austen (1669), Thomas Sylliborne (1673) and John Baker (1682).

John Feverstone the older was the miller in 1766, when the lease was renewed; Richard Tilbe was the owner at this time.

The crown wheel drove two layshafts, which powered various machines, including a "Ureka" winnower and an oat crusher by Ganz & Co., of Budapest, Hungary.

A possible mill site, a building was marked on a map of Leeds Castle dated 1748 on the island which lies above Keeper's Cottage.

In 1733, Sir Roger Meredith, Baronet, of Leeds Abbey leased land in Hollingbourne to James Whatman with permission to erect a new dwelling house and papermill.

In 1628, Thomas Fludd and Ralphe Buffkin sold the mill to William Cage of Lincoln's Inn, Middlesex.

This mill was built by the Cage family in the late 1820s on a piece of land called Byfrance, part of the Milgate estate.

The mill was sold for house conversion in 1986, at that time only the frame of the waterwheel and pit wheel survived, all other machinery having been removed.

It was part of the manor of Newnham Court (owned by Sir John Astley), which had been in the ownership of Boxley Abbey.

Overloppe Mill was sold for £493 by Simon Smythe of Tenterden to John Fletcher of Boxley in 1640.

Gill was declared bankrupt in 1731 and the mill passed to James Brooke, the chief mortgagee.

The mill was sold by James Whatman Jr in 1792 to Thomas, Robert and Finch Hollingworth of Maidstone for the substantial sum of £32,000.

Ownership of the mill passed from Thomas Hollingworth through his sons and thence through their nieces until eventually Major William Pitt was the sole owner.

In 1510 the miller was one of 22 tenants of the Archbishop of Canterbury who considered his rent was excessive and refused to pay.

Messrs Bradley, Taylor and Youngman were the millers in 1957, but the mill had ceased to work by water power by then.

[1][21][24][25] Two streams rise at Harrietsham and each powered a watermill in the village before joining the River Len.

The Hollingbourne Stream rises above the village and powered four watermills before joining the River Len.

A stream rises north of Bearsted and powered two watermills before joining the River Len.

[1][5][6][7][27][28][29] The Hollingbourne Stream rises at the foot of the North Downs, and flows for 1+1⁄4 miles (2.0 km) to the River Len.

A mill may have stood on this site since 980, when King Edelstane gave Holyngbourne to Christ Church, Canterbury, and almost certainly since Domesday.

The lease of the mill was in the ownership of John Spencer Culpeper and passed to Francis Child in 1762.

The main axle of the watermill broke in 1925 thus bringing an end to the working life of the mill.

In 1609, the estate was sold to Sir William Meredith, in whose family it remained until the eighteenth century.

The waterwheel drove three pairs of millstones via two lineshafts, each driven by a 2 feet (610 mm) diameter cast-iron gear.

One shaft drove a single pair of 4-foot-diameter (1.2 m) French Burr millstones by a 5-foot-diameter (1.5 m) cast-iron face gear with wooden cogs and the other shaft drove two pairs of French Burr millstones by 5-foot-6-inch-diameter (1.7 m) cast-iron face gears with wooden cogs.

It was in existence during the first half of the eighteenth century, appearing on a map of 1707 which was partly resurveyed in 1746.