Darley Abbey Mills (South Complex) Long Mill, Middle Mill, East Mill, West Mill, Engine House And Chimney, Tollhouse, Bobbin Shop And Drying Shed

Darley Abbey Mills (South Complex) comprises a former cotton textile manufacturing complex on Old Lane in Darley Abbey, built from around 1792 and continuously remodelled and enlarged between 1788 and circa 1840, with further alterations in the late 19th and 20th centuries. The complex was built by the Evans family and includes Long Mill, Middle Mill, East Mill, West Mill, an Engine House and Chimney, a Bobbin Shop, a Drying Shed, and a Tollhouse. The buildings are constructed in red brick and ashlar gritstone with slate roof coverings.

The complex forms part of an extensive multi-phase cotton textile factory and was powered originally by watercourses flowing through the site, fed by the River Derwent. The site is subdivided by Old Lane and consists of a functionally related group of mills with ancillary structures accumulated at the south-west corner.

Long Mill is a 17-bay mill aligned north-south of 5 storeys and an attic, rebuilt and enlarged following fire damage in 1788. It features various patterns of timber windows, some with cast iron opening lights, beneath shallow brick arched and flat stone lintels. The lower floor is supported by wooden transverse beams resting on a single rank of cruciform-section cast iron columns set into detached capitals. Exposed timber surfaces and beam soffits are covered with thin iron sheets fixed by nails. The attic floor is supported by a matrix of wooden beams rather than transverse beams, while the roof structure is supported by timber queen-post trusses with cambered collar beams, protected by iron sheeting. The lower framing of a bell tower survives at the northern end of the attic floor.

Middle Mill is a 6-bay eastward addition to Long Mill of 5 storeys, probably dating from circa 1796-1801. It has various patterns of timber windows, some multi-paned with cast iron opening lights, beneath shallow brick arched lintels. A wide stone-framed wheel race arch appears below the southern elevation. The floors and roof were rebuilt in the mid-20th century following a fire, though a large blocked arched opening indicates the position of a former waterwheel.

East Mill is a 6-bay, 5-storey eastward continuation of Middle Mill, slightly wider in plan and probably dating from circa 1818-19. It has various patterns of timber windows, some with cast iron opening lights, beneath shallow brick arched lintels. The interior features fire-proof construction with cylindrical cast iron columns supporting iron beams and brick jack arches, together with an iron roof. The roof structure is framed by iron trusses consisting of principal rafters and a cruciform-section king post rising from a low collar with slender spandrel braces at the ends.

West Mill is a 7-bay by 7-bay L-shaped westward 4-storey plus attic addition to the central bays of Long Mill, thought to date from 1819-21. The interior employs fire-proof construction with cylindrical cast iron columns supporting iron beams and brick jack arches. The brick jack arches run longitudinally in the link block and transversely in the return, maintaining a single alignment of vaulting but requiring three round cast iron columns to each cast iron beam in the link and only one to the transverse beams in the return. The top floor consists of timber joists spanning between iron trusses, with both joists and attic-level studwork protected by metal sheeting. The roof structure is framed by iron trusses with cranked tie beams, principal rafters, purlins and two sets of cruciform-section struts, all in cast iron, together with twin wrought-iron king-rods. The shorter east-west arm attached to Long Mill has straight purlins and cast iron common rafters, while the longer north-south arm has fish-bellied purlins and timber common rafters.

The Engine House and Chimney is a 4-bay by 1-bay single-storey southward addition to Middle Mill dating to circa 1896. A double doorway with semi-circular fanlight occupies most of the southern elevation. The interior is match-boarded with stop-chamfered timber roof trusses. It was built to house a 250hp horizontal single tandem condensing steam engine by John Musgrave & Son of Bolton. An adjacent detached circular brick-built chimney has a string course to its cap.

The Bobbin Shop is a 4-bay single-storey structure to the south of East Mill dating to circa 1840. The original windows have iron lintels. The interior features a cast iron and wrought iron roof with shaft hangers.

The Drying Shed is a tall single-storey structure, formerly with slatted sides, and has a ventilated roof.

The Tollhouse is an octagonal single-storey rendered brick structure with a slated roof and a single tall chimney stack, dating to the late 18th or early 19th century. Although latterly a tollhouse, it probably originally served as a watchman's lodge guarding the entrance to the mills.

Long Mill is shown on a plan of 1782 by Benjamin Outram, powered by a cut from the River Derwent, and was rebuilt in 1788 following a fire. Its late 18th-century cast iron columns are among the earliest surviving in situ examples, and it represents the earliest known example of a textile mill using metal sheeting for fire resistance. The attic was adapted around 1791 for use as a schoolroom, perhaps providing the model for the noted example at North Mill, Belper.

The southern complex was a highly significant water-powered site with at least four large waterwheels and latterly five water turbines—two twin and three single—totalling over 435 horsepower. Long Mill and West Mill retain significant evidence of the later phases of their complicated power transmission systems, including rope slots, shaft hatches, bearing boxes and shaft hangers. Blocked wheel arches appear in the walls of Long Mill and West Mill, while open arches appear below Middle Mill, all providing evidence of former waterwheels, some of which reportedly worked until circa 1923.

This complex forms part of the textile manufacturing site at Darley Abbey, which traded under the name of Boars Head Mills. As an entity, the complex is exceptional in its completeness of survival and displays important aspects of the development of fire-proofing technology for textile factories. The site forms part of a closely related network of pioneer textile manufacturing sites in the Derwent Valley. Thomas Evans was an associate of Richard Arkwright of Cromford, and the Evans family was related by marriage to the Strutt family, who had mills in Belper, Milford and Derby. Darley Abbey sits alongside these settlements in terms of both historic and architectural significance, retaining all of its major early buildings as well as 19th-century additions, many of which are distinguished by the use of iron roofs.