Until the early 19th century, the usual method of producing wrought iron involved a charcoal-fired finery in a finery forge.  In the beginning of the 19th century this became an obsolete process and was slowly replaced by the coal-fueled puddling process.  However, charcoal continued to be used in some forges after most of the iron industry had abandoned it for coke.  
In 1813 when John Bradley & Co. (whose leading partner was James Foster) took over forges at Eardington in Shropshire, a potting and stamping forge, they reverted to using charcoal.  In 1820, he bought Hampton Loade Forge, which then became a tinplate works and in 1826 another charcoal forge.  This was followed by other charcoal forges at Horsehay in 1832 and at the Old Park ironworks of the Botfield family about 1826.  Cookley Forge in the Stour valley also reverted to charcoal working in 1814, supplying wire and tinplate mills.  
By the 1830s, these forges were sometimes producing over 2000 tons of iron per year, compared with a few hundred from earlier finery forges.  It is likely that these forges were using a more efficient variety of hearth, which from Swedish usage has come to be known as a Lancashire hearth.