The Darkhill Site on Gorsty Knoll

Scheduled Monument No 28878

Location NGR: SO 5901 0880

Address Parkend Rd, Coleford GL16 7LX, UK


The easiest way is to follow the cycle trail that uses a former railway from Parkend to Coleford.

By car it is best reached by taking the B road from Coleford towards Parkend, and from it taking the right turn towards Ellwood and Sling until the Forestry Commission car park entrance appears on the right. The best viewpoint is gained by walking back along the cycle way.

Plan and interpretation from: Webb, K., 2001. Robert Mushet and the Darkhill Ironworks.

This Scheduled Monument belongs to the Forestry Commission. In 2015 the Trust undertook masonry repairs, and, in partnership with the Commission, supplied on site interpretation.


In 1818, the metallurgist David Mushet built a small cupola furnace here for experimental work. Later, his son Robert Mushet used part of the site for making crucible steel on a commercial scale. Around 1845 a substantial and productive blast furnace was built, but due to differences between the three Mushet sons, it was put up for sale in 1847. No new owners emerged. There was also a brick works

Robert Mushet and the problem of Bessemer Steel

Robert, the youngest son, continued his crucible steel making. As elsewhere, his steel was produced as cast steel in batches of around 70 pounds per crucible. He also continued with his research both  here, and at his laboratory in Coleford. In 1856 the chemist Henry Bessemer announced his invention for making steel in bulk by processing molten iron direct from blast furnaces into his Bessemer converter. He sold expensive licences to iron masters who found that it did not work. Specimens of the failed product were brought to Robert Mushet. His metallurgical knowledge soon solved the problem and bulk steel making flourished. The first ingot of Bessemer-Mushet steel was made at Darkhill and taken to Ebbw Vale where it was rolled to produce the world’s first steel railway rail.

Up to that time rails were made of wrought iron and rarely lasted more than a few months.. Mushet’s rail was laid in Derby Station and it lasted for 11 years. However, Mushet’s patents were faulty and whilst Bessemer made a fortune, Mushet did not.

The world’s first machine tool steels

Robert Mushet continued with his analytical research and in 1868 he invented an alloy of steel and tungsten. Known as ‘RMS’, or Robert Mushet’s Special Steel, it revolutionised productivity in engineering. Lathe tools made from RMS did not need constant re-sharpening; they also permitted deeper and wider cuts and they doubled lathe speeds. Production began in new buildings called the Titanic Steelworks adjacent to Darkhill. Later the operation was moved to Samuel Osborne’s works in Sheffield which became a very successful enterprise.


Plan and interpretation from: Webb, K., 2001. Robert Mushet and the Darkhill Ironworks.

A: Blast furnace remains. B. Probable ventilation engine house. C & D. Charging platform and incline to the furnace top. E. Smiths shop. F. Pug or crushing mill. G. Crucible furnace area. H. Brick kiln base. I & J.  Brick making. K. Brick kiln base. L. Store for brick clay.

Sources for more information.

Lange, F. E. 1913. Bessemer, Goransson and Mushet: A contribution to technical history. Manchester Memoirs, Proc Manchester Literary and Philosophical Society, Vol. lvii. No. 17.

Boucher, J. N. 1924. William Kelly: A true story of the so-called Bessemer Process. Published by the author. Greensburg, PA.

Osborn, F.  M  1952. The story of the Mushets. Thomas Nelson. London. ISBN 1 903599 02 4.

Bishop, W. P. 1959.   The beginning of cheap steel. United States National Museum Bulletin, 218. Smithsonian Institution.

Anstis, R. 1997. Man of iron- man of steel: the lives of David and Robert Mushet. Privately published.  Coleford.

Webb, K. 2001. Robert Mushet and the Darkhill Ironworks. Black Dwarf, Lydney. ISBN 1 903599 02 4. A very useful guide to the site with many illustrations.




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