The Romans brought aqueducts, wealth, security and hot baths to Britain but the best thing they did for the population was to leave, a historian has suggested.

Studies of graves in cemeteries from the 400AD to 650AD show that Britons, on average, lived for around two years longer following the fall of the Roman Empire.

Robin Fleming, professor of history from Boston College in the US, said that once Britons were no longer forced to pay taxes they were able to eat more nutritious food which increased longevity.