"Holloways are lower than the surrounding field levels because they have been created by movement of people – not deliberately, but over thousands of years," explained Jefferies, as we stood around 10ft below the adjacent countryside. Holloways are found all over the world, he explained, but a variety of factors – including soft bedrock and a long history of habitation – have come together to make southern England, and Dorset in particular, a hotspot. (There are around 40 miles of holloways in Dorset, by Jefferies' reckoning, out of around 1,000 total holloway miles in England.)