Britain's industrial economy did not collapse when the Romans left and went on to enjoy a Viking-age industrial boom, a new study finds, undermining a stubborn 'Dark Ages' narrative.
It has significant implications for our wider understanding of the end of Roman Britain
Professor Martin Millett
The Romans have long been credited with bringing industry to Britain involving large-scale lead and iron production. But it has been unclear what happened once the Romans left around 400 AD. It was generally assumed that industrial-scale production declined, as no written evidence for lead exploitation after the 3rd century exists.
To test this assumption, researchers from the Universities of Cambridge and Nottingham examined a five-metre-long sediment core from Aldborough in Yorkshire, the Roman tribal town of the Brigantes and an important centre of metal production. Their findings, published in the journal Antiquity, confirm that metal production did not collapse immediately after the Romans left Britain.
Professor Martin Millett, from Cambridge's Faculty of Classics and Fitzwilliam College, said: "This collaborative work which forms part of a long-term project at Aldborough adds a new dimension to our understanding of the history of this important Roman town in the immediately post-Roman period. It has significant implications for our wider understanding of the end of Roman Britain."
The study's findings indicate that metal production in Britain continued long after the end of the Roman period and did not decline until a sudden crash around 550-600 AD.
The researchers found low levels of lead and iron production in the 4th to the early 5th centuries AD, but a large continuous rise in iron - and to a lesser extent, lead smelting through the 5th to mid-6th centuries - with the same ore sources and use of coal as in the Roman period. This undermines the popular belief that post-Roman Britain was a 'Dark Age' in which industrial production regressed to pre-Roman levels.
The cause of the sudden crash remains uncertain, but textual evidence from the Mediterranean and modern-day France (from the mid-late 6th century) shows that this period saw multiple waves of bubonic plague, and perhaps smallpox. These findings combined with DNA evidence from Edix Hill cemetery in Cambridgeshire show that bubonic plague was killing people in eastern England from the 540s, and this period marked the point of transformation at Aldborough.
Lead author, Professor Christopher Loveluck from Nottingham's Department of Classics and Archaeology, says the Aldborough sediment core "has provided the first unbroken continuous record and timeline of metal pollution and metal economic history in Britain, from the 5th century to the present day."
The cylinder of slowly accumulated silts was extracted from a paleochannel of the River Ure. Previous metal pollution records have been extracted far from their sources - for instance upland peat cores or mountain and polar glaciers - but this data comes from the very epicentre of production.
The researchers analysed the core alongside excavation evidence and knowledge of landscape changes at Aldborough over the last two millennia. The study benefited from the expertise of Charles French, Emeritus Professor of Geoarchaeology at Cambridge, who applies archaeological techniques and micromorphological analytical techniques to the interpretation of buried landscapes.
The study indicates that lead and iron production was very active again before the Vikings arrived and expanded under their control. Textual and archaeological sources already suggest that there was a growing focus on domestic economies rather than international trade by that time. It has been difficult to prove this at a macro-scale, but the new results show a boom in raw metal production between the end of the 8th century and through to the 10th century, revealing regional-level economic growth, which has never been measured beyond single sites before.
The study goes on to show a decline in metal production through the 11th century with renewed large-scale growth in lead and iron production reflected again from the mid-12th to early 13th centuries. Results corroborate annual-written sources for increased Yorkshire and wider British lead production from the 1160s-1220, and comparable pollution increases attributed to Britain for these decades recovered previously from Swedish lakes and Alpine ice-core research from Switzerland.
Following a decline in the 14th century, the researchers found evidence of another recovery in production which was cut short by Henry VIII's Dissolution of the Monasteries from 1536-38.
"It became uneconomical to make fresh metal because it was ripped off all the monasteries, abbeys and religious houses," Professor Loveluck explains. "Large-scale production resumed in the later 16th century to resource Elizabeth I's Spanish and French wars."
The Aldborough Roman Town Project, directed by Dr Rose Ferraby - an author of the new study - and Professor Martin Millett, from Cambridge's Faculty of Classics, has carried out nearly 120 hectares of magnetometry inside the town and beyond, to establish a landscape scale view of the sub-surface archaeological remains of the town, its defences, road system and extra-mural areas. It has also used Ground Penetrating Radar more selectively within the town to reveal details and depths of the Roman buildings. Since 2016, a number of excavations have been carried out, re-examining earlier trenches.
Funding
The research was funded by The British Academy and the University of Cambridge.
Reference
C. P. Loveluck, M. J. Millett, S. Chenery, C. Chenery, R. Ferraby, C. French, 'Aldborough and the metals economy of northern England, c. AD 345-1700: a new post-Roman narrative'. Antiquity (2025). DOI: 10.15184/aqy.2025.10175
