A sonar probe of the bed of the English Channel has produced evidence that Britain may have become an island is less than 24 hours, the Daily Telegraph reports.
The survey, led by Imperial College London's Sanjeev Gupta, revealed the "remains of a huge valley, running south-west from the Strait of Dover" plus "deep bowls, scour marks and piles of rubble on the sea bed that may have been caused by a torrent of water".
Dr Gupta explained: "In places, this valley is more than seven miles wide and 170 ft deep, with vertical sides. Its nearest geological parallels are found not on Earth but in the monumental flood terrains of the planet Mars.
"This suggests the valley was created by a catastrophic flood following the breaching of the Dover Strait and the sudden release of water from a giant lake to the north."
Specifically, Dr Gupta's proposes that Britain and France were "linked by a high ridge of chalk hills, running roughly between Dover and Calais". Between 400,000 and 200,000 years ago, the aforementioned monster lake, "hundreds of feet above sea level", breached the chalk ridge and made good its escape towards the Atlantic.
Dr Gupta's theory - outlined in his book Homo Britannicus: the Incredible Story of Human Life in Britain, published next week - challenges the traditional theory that the British and the French had plenty of time to work up to mutual enmity as Blighty and the continent slowly parted company.
Rather, it seems our earliest inhabitants woke up one morning to find their former neighbours taunting them about superior cuisine from the safety of the newly-formed English Channel's far bank, provoking the first Brits to storm off and invent the longbow. ®