In 1763 John Guest and Isaac Wilkinson started the Plymouth Works, on land leased from the Earl of Plymouth, they failed to make it a success, and sold it two years later, to Anthony Bacon,  this was  about  the same time as Bacon built his first furnace at Cyfarthfa. Richard Hill (Bacon's brother-in- law)  was appointed manager of the works. Following Bacon's death in 1786, the works were left to his son's, who then sold it to Richard Hill. The works prospered under Hill's management, the metal produced at Plymouth was considered to be the finest in South Wales. on the death of Richard in 1818, His son Anthony Hill took control of the works. The Bessemer process for converting Pig-Iron into Steel, was first partially developed by Anthony Hill. He died in 1862, and the company was taken over by Messrs. Fothergill, Hankey, and Bateman. This partnership allowed the company to rundown for various reasons, which led to it's closure in 1882