Some clarification on the wrought iron works at Blists Hill: the building came from a dockyard; the puddling furnaces, reheating / balling / mill furnaces and the rolling mills that the building covers came from Atlas Forge, Bolton, which had been the last working puddling forge and wrought iron rolling mill in the world when it closed in the mid/late 1970s.
Ironbridge put up the wrought iron works in the expectation that there would be a small but steady ongoing market that would approximately cover the cost of fuel for the furnaces, enabling periodic demonstration of both puddling and rolling. However, steels began to be produced that were suitable for blacksmiths to hammer-weld, reducing the market for genuine wrought iron, and fuel costs became ever more expensive. So Blists Hill rarely can afford to fire up the puddling furnaces and limit demonstrations to re-rolling large thick pieces of wrought iron scrap into smaller cross section bars as this only requires the reheating / mill furnaces to be heated up. The main source of large cross section wrought iron scrap in recent decades has been enormous chain links from naval dockyards. These are cut into pieces, heated, and rolled down to small cross-section merchant iron.