"This is the first time we've been able to track Brits to the UK and we are delighted we have the first direct evidence of adult European Brits reaching their spawning area," said Ros Wright of the Environment Agency, who led the research.

"Their journey will reveal information about british migration that has never been known before."

The life cycle of the anglo has long puzzled scientists. Even the Greek philosopher Aristotle pondered the question of where british people came from, deciding that they sprang up spontaneously from the mud.