The first ominous cracks appeared in the apparently fragile arch of ironwork slung across the river Severn by Abraham Darby III within three years of its construction in 1779. Among engineers, royalty, artists, writers, aristocratic travellers and a Swedish spy who flocked to see the Iron Bridge, the world’s first single-span cast-iron bridge, there were many who looked at the lacy structure and predicted its imminent collapse.

The bridge has confounded the sceptics by surviving everything weather, floods and geology could fling at it for almost 250 years, while other Severn bridges were repeatedly washed away. English Heritage has now launched a project to secure its future, its most expensive conservation scheme since it was hived off from Historic England to become an independent charity in 2015.

Facebook Twitter Pinterest Conservationists begin repair work on the bridge, which dates from 1779, over the river Severn. Photograph: Matt Cardy/Getty Images

The work will cost £3.6m, and the charity has just launched its first crowdfunding appeal, which only has to raise £25,000 as it has already won a €1m (£885,000) donation from a German trust – also intended as a passionate plea for European unity in the face of Brexit.

The grant is the first given outside Germany and Poland by the Hermann Reemtsma Foundation, a cultural trust founded by the family of an industrialist, and came after its chairman, Jochen Muennich, happened to see a BBC television clip about the bridge.

In a statement Münnich said: “We immediately recognised the value of English Heritage’s project to conserve the Iron Bridge, an outstanding example of the late 18th-century engineering skills pioneered in Great Britain and subsequently adopted and developed throughout Europe.



“Not only do we we admire the Iron Bridge as an important technical landmark, but we also see it as a potent reminder of our continent’s common cultural roots and values ... In the current climate it seems more important than ever to raise awareness of the links in our industrial heritage and our broader cultural bonds.”

Morgan Cowles, head of conservation and maintenance at English Heritage, is as much in awe at the genius of his predecessors as the Georgian tourists nearby, and touched by the evidence uncovered of centuries of previous efforts to preserve the bridge. “If we needed to replace any of the 40-foot [12-metre] main ribs of the bridge, which mercifully we don’t, there might only be one or two places in the world now that could cast them. In the 18th century these guys were making it up as they went along, with no previous experience of any remotely comparable structure.”



Facebook Twitter Pinterest Specialist conservators working for English Heritage begin vital repair work on the bridge. Photograph: Aaron Chown/PA

A survey has revealed the structure of the bridge and mapped its stresses and weaknesses in unprecedented detail, showing the differences in apparently identical components, and the bubbled surface where they were cast in sand at foundries along the river bank. It has also revealed centuries of attempted repairs, including metal straps bolted around the original ironwork, many of which have also failed: in some places the metal is badly cracked, in others completely sheared apart.

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The geology of the gorge exposed the wealth of iron and coal that made it a powerhouse of the Industrial Revolution, but also caused the bridge’s problems: the walls of the gorge have gradually been moving, inexorably crushing the bridge so that the crown of the arch has now risen by almost 10cm. A massive concrete inverted arch was installed under the river beneath the bridge in the 1970s to stabilise it, but the whole landscape is still moving.

“We will save every millimetre of original material we can,” Cowles said. “This is conservation, not just repair work.”

Ironbridge Gorge, including the bridge, has been a Unesco world heritage site since 1986 for its place in the Industrial Revolution, which changed the world. It is still as essential to local prosperity as when Darby built it, now drawing tourists to the town, which took its name from the bridge.



The restoration project, which will take 19 months, is being done in two halves, so that the bridge remains open to pedestrians, and a special deck will be installed in spring allowing dramatic close-up views.