Angles and Saxons came to Britain as peaceful settlers after the collapse of Roman authority caused civilisational “wipeout” but went on to subjugate the Britons centuries later, a scientist says.
John Lambshead, a biologist and retired senior research scientist at the Natural History Museum, has analysed genetic and climate studies alongside historical and archaeological sources to put forward a new model of how large parts of Roman Britain became Anglo-Saxon England and how Brythonic and Vulgar Latin were replaced by Old English.
According to Lambshead, events long after after the end of Roman rule around 410AD are key to explaining a cultural shift to a common English identity and the use of English rather than Welsh or a Romance language. “Something happened around 800, and when you start to look at that, it all makes sense,” he said.
The reasons why Britain did not follow Gaul in preserving Latin and extensive trappings of Roman culture in the post-Roman period have vexed historians and archaeologists for years. Traditional accounts depicted a massive invasion of Angles, Saxons and other groups from today’s northern Germany and Denmark. The Britons were supposedly slaughtered, enslaved or forced west into Wales, Cornwall and Brittany after naively hiring Saxon mercenaries to fight marauding Picts and Scots. British resistance under commanders resembling the legendary King Arthur was said to have been dogged but ultimately futile.
On the other hand, some modern interpretations hold that few Saxons or Angles ever crossed to Britain and Britons adopted German-style goods and the Germanic Old English language after they came into vogue through trade links and small-scale settlement.
Lambshead said there was no evidence for an Anglo-Saxon invasion, and this would have been beyond the organisational and technological capabilities of 5th- and 6th-century Germans with only rowing boats for the crossing. However, Saxons had certainly crossed the North Sea in small raiding parties for centuries, and studies indicating that many English people today have 10-40 per cent German-like DNA indicate that migration occurred, probably over a number of generations.
He said the findings of a 2015 genetic study suggesting that Britons and Germanic people in Britain only mixed on a large scale after 800AD made sense if the two communities originally lived apart in areas that had become depopulated. This was likely to have occurred in southern and eastern Britain if Roman administration, the security apparatus and the coin-based economy all broke down catastrophically following the failure of the usurper Constantine III.

Constantine, allegedly a common soldier, was declared emperor by the army in Britain in 407 and led British-based troops into Gaul and Italy, where they were defeated. Lambshead suspects that he was seeking silver reserves to pay his troops after regular shipments of coins to Britain ceased. Roman rule of Britain is thought to have ended around 410 when the legitimate emperor Honorius, facing barbarian invasions and rebellions closer to home, washed his hands of the island.
In his book The Fall of Roman Britain and Why We Speak English Lambshead argues that, across the empire, Roman power amounted to a military dictatorship after climate change in the third century led to reduced agricultural output. There is archaeological and textual evidence that Roman Britain was heavily militarised, with fortified towns suggesting a rebellious population. Once the Roman army had gone for good, Lambshead said people could no longer have been forced to work on imperial estates or paid in cash for labour.
In his analysis, large agricultural estates concentrated in the more Romanised south and east disintegrated and their output crashed “causing widespread hunger, social dislocation, violent struggles to secure remaining food, emigration out of the region, and general depopulation.”
He said the Britons most likely to have remained in these regions lived in isolated villages and were already accustomed to subsistence farming. Nevertheless they were unable to produce goods such as iron nails that they had relied on Roman industry for and they survived only as the “fag end” of a failed state. Migrants from across the North Sea, attracted by empty lands more fertile than their own, brought with them a “simple but functioning” culture that allowed them to prosper in their own separate villages.
In the Romano-British areas that became Wessex magnates started to identify with their bucellarii
John Lambshead
He infers that population pressure in the 7th and 8th centuries caused the Anglo-Saxons, who had in the meantime developed hierarchical societies with kings and warrior elites, to seize land from the impoverished and less organised Britons. The Britons remained on the land as unfree labourers with every incentive to adopt the language and customs of the free Anglo-Saxon elite. This fits with the archaeological theory of a Middle Saxon shuffle, which claims that many early Anglo-Saxon villages were abandoned in favour of alternative sites with superior natural resources.
Over time, Lambshead said, Anglo-Saxons and Britons would have intermarried and Old English would have completely displaced low-status Brythonic, the forerunner of Welsh. He points to Iceland as an example of another territory populated by speakers of both Germanic and Celtic languages — via Old Norse-speaking Viking settlers and British and Irish slaves — where British and Irish genes remain prevalent but Celtic languages have left little obvious trace in modern Icelandic.
He added that processes in Britain probably differed widely by region. “What happened in the west was different from what happened in the south and north. In the north, what seemed to happen was the Roman army became Brythonic tribesmen. The people in charge at Vindolanda [a fort near Hadrian’s Wall] by about 450 were described by Celtic legal names. But in the the southeast there’s nothing. It’s just total wipeout, collapse.
“In the west it’s a bit more mysterious. I think that in the Romano-British areas that became Wessex magnates started to identify with their bucellarii [armed retainers], many of whom would be German — former Roman soldiers. You might have a situation where the king actually had three names: a Brythonic one, a German one and a Latin one, depending on who he was talking to.”