Roman iron workings in the Severn valley were extensive. The value of iron was great, and often used as currency. In a Domesday survey Gloucester paid tribute in bars of iron. In the Wyche Cutting, Malvern, in 1856, 200 bars of iron was found. Evidence of them being currency shown by each being a multiple of weight. At Worcester, great quantities of iron slag and charcoal remains are evidence of a century or more of iron workings. The use of charcoal for smelting was essential, and the great forests around and the Severn for transport made it ideal for the making of iron.
In the 16th century the breakup of ecclesiastici estates and the arrival of the new technology in the iron trade from Europe, led to great economic activity on or near the Severn, for there the iron trade still found charcoal and iron in abundance; and further more, the superb 'free' transport of the Severn. During the second half of the 16th century the iron trade had migrated from Sussex due to the denuding of the woodlands there. Great technical changes had already took place in the making of iron, and the separation of the processes took place from medival times 'bloomeries' were set up wherever timber for charcoal and iron was available (as in the Wyre Forest), and bar iron forged directly on an anvil with a heavy tilt hammer and water close by, but with the coming of the blast furnace things changed. The blast furnace needed maximum fuel but only a minimum of water to operate the bellows. Consequently, forges tended to be set up on substantial streams to work the tilt hammers, but the furnace needed abundant charcoal, and was built elsewhere.
The new blast furnaces needed vast amounts of charcoal, and the new owners of the ecclesiastical estates entered the profitable iron trade. Worcestershire became the centre of the arms trade. Every stream that could be used drove the water wheels, and dams were made across villages to create pools to form a 'head of water'. Some idea of the activity in this area was made in 1620 by Dud Dudley, who estimated that 20,000 smiths were at work within 20 miles of Dudley. The situation was becoming desperate, for the salt trade at Droitwich was also using vast amounts of timber. By 1558, an Act forbidding the use of timber for 'coals for the working of iron' growing within 14 miles of the rivers Thames, Severn and Wye. Worcestershire which in the 16th century was almost denuded, and the iron trade moved north into Shropshire.
All around Dudley were great quantities of coal but used only for domestic puposes. The answer to the furnace problem came with the roasting of coal, which removed the sulphur, and making and using coke instead of charcoal. Dud Dudley (among others) was experimenting with pit coal and several kinds of iron ore, and he obtained his first patent in 1621 for his furnaces at Pensnett, Cradley and Himley, but was greatly troubled by patents from rival ironmasters, whose mobs destroyed his furnace. Other ironmasters experimenting at the time were 'Fiddler Foley' and his sons Thomas and Robert, Ambrose Crowley and others.
Abraham Darby gets the credit for the great breakthrough in 1701 at Ironbridge, but it is known that Darby's grandfather worked for Dud Dudley and would undoubtedly have known of Dud's experiments. In 1629, Richard Foley set up the first slitting mill in the Midlands at The Hyde.
In the 18th century, Stourbridge had become a focal point in the iron industry. Bewdley on the Severn became the actual market and depot, but Stourbridge, situated on the fringe of the great iron manufacturing area stretching from Wolverhampton to Bromsgrove, and backed by numerous forges and slitting mills all within easy reach of the Severn, was the centre of the iron trade.