Overview: In East Sussex, the expert walker sets off from the village of East Dean, as she explores one of the longest undeveloped coastlines on the south coast - one that is disappearing at an erosion rate of almost one meter a year. During her three-hour walk Julia discovers the area's rich social history at seaside settlement Birling Gap, learns of the mystery of Sherlock Holmes' retirement, and hears how a lighthouse had to be shifted 17 metres back from the cliff edge.