Monument record TQ 54 NE 33 - Leigh Gunpowder Works

Leigh Gunpowder Works est 1807 (or 1811), closed 1930s. Founded by members of the local Burton and Childern families together with Sir Humphrey Davy, being bought by Curtis and Harvey in 1859. In later years produced the relatively unusual 'brown' powder as well as black powder, production of which ceased in 1897. The final years of production concentrated on smokeless sporting powder. (1) Overall layout of works well preserved (though part of site has been cleared to build Smithkline Beecham Pharmaceuticals works) but there are no standing buildings, only leats, blast banks, building footings and some bedstones. The works is arranged around a canal running off the Medway at TQ 5620 4615 and returning to it at TQ 5786 4669. This was used both for powering water wheels and for transport.(1)

The early complex is recorded as containing workers cottages, two double mills, and a managers house. By 1840, the site had expanded and nine workers' cottages existed, the figure rising to 15 by 1851. In 1859, the site is recorded as containing at least 24 buildings, including the workers' cottages and four mills (summarised from source, 3)

The site is privately owned and is an overgrown wilderness, with several remains of wheel pits, arranged in parallel between upper and lower mill streams. There is also a more substainial remains of apparently later water powered incorporating mills with fragments of iron edge runners lying nearby. (2)

The Leigh mills were established in 1811, after being bought by Curtis's & Harvey, clack powder was produced for the military and later smokeless sporting powders were made, this manufacturing was transferred to Tonbridge when the works at Glen Lean in Argyll closed. The factory closed and become derelict after 1931. (2)

In 2005 the site was investigated by Leigh & District Historical Society. The site was overgrown, making the identification of many features challenging. The foundations of several buildings were located, alongside three earth mounds which had been constructed to prevent blast damage to the site. The lines of a derelict tramway, probably established in 1885, were also located, visible as straight raised pathways in various locations. Around a mile and half of track originally existed during the First World War when the tramway was used to transport material around the site.
Artefacts which were identified during the investigations included some elements of machinery and a heap of heavy ceramic retorts which were used to hold caustic materials required for explosives.
The mill stream (recorded as 4-5 metres wide and 800 metres in length) was observed to contain the remains of a number of sluices. Several small waterways led off the tail stream which were interpreted (7) as having been used to transport gunpowder around the site. (7)

In 2013 AOC Archaeology carried out an evaluation. Remains of structures relating to the 19th century gunpowder works were found across the site. (3) Further excavations in 2015 revealed the remains of a Boiler House for powering the mills on site in the late 19th century, and a group of structures associated with the manufacture of guncotton/cordite; a Wet Gun Cotton Store, an industrial Alcohol Store, a Poaching House, a Wringer House and a Box Store of a later date. (5)

<1> G Crocker Gunpowder Mills Gazeteer 1988 (Gunpowder Mills Study group) (OS Card Reference). SKE43449.

<2> The Cranstone Consultancy, 1993, Tonbridge, Leigh Mills: Gunpowder Mills Gazetteer (Unpublished document). SKE17149.

<3> AOC Archaeology, 2013, Gunpowder Mills, Leigh, Tonbridge, Kent: Archaeological Evaluation Report and Historic Building Record (Unpublished document). SKE25219.

<4> CgMs Consulting, 2013, Cultural Heritage Impact Assessment: Gunpowder Mills, Leigh, Kent (Unpublished document). SKE25218.

<5> AOC Archaeology Group, 2017, Archaeological Investigation at Gunpowder Mills, Leigh, Kent, An Excavation and Analysis Report (Unpublished document). SKE52716.

<6> The Cranstone Consultancy, 1993, Monuments Protection Programme: The Gunpowder Industry Combined Steps 1-3 Report (Unpublished document). SKE17244.

<7> Leigh & District Historical Society, History of Powder Mills (Website). SKE58995.