This is Dead Man's Lane, which was used to transport the dead from Mapperton to the bigger village of Netherbury for burial.
When the plague struck Mapperton - noone is sure whether it was during the 14th century plague or the one that struck in the 16th century - the villagers of Netherbury blocked the way so the plague victims didn't get buried in their village - for fear of infection. Therefore the deceased were buried in a pit dug on South Warren Hill between the two villages. You can still see the cobbles from all those centuries ago. It's a very atmospheric path!