Firth and Sons was formed by Mark and Thomas Jnr. Firth, in Sheffield, in 1842. After a succesful start, the company moved to the Norfolk Works, still in Sheffield, where they manufactured files, cruicible furnaces and the largest rolling mill in Sheffield. Business grew and moved into the armaments market, the company installing two Nasmyth Steam forge hammers in 1863 which were used to forge guns. In 1902 Firth and Sons exchanged shares with John Brown & Company exchanged and the two came to a working agreement, the companies continued under their own management until they finally merged in 1930.