Started as the MERTHIR FURNACE by Thomas Lewis of Llanishen in 1759. John Guest from Broseley in Staffordshire was appointed in 1767, and became a partner in 1782. After this time the Guest's influence progressed and by 1815 he dominated the company, with five blast furnaces produced 15,600 tons of pig iron. By 1823 with ten blast furnaces produced 22,287 tons of pig iron. In 1840 the works had 5000 employees. By 1845 Dowlais Ironworks was the biggest ironworks in the world, with 18 blast furnaces producing 88,400 tons yearly and 8800 employees.  In the 1850s it took out the first license with Bessemer and Longsdon to use Henry Bessemer's process to produce steel. The first Bessemer steel was rolled there in 1865. The original Dowlais works at closed in the 1930s, but production continued at the Ifor Works until 1987.

Dowlais Iron & Steelworks

Ifor Works