It’s called Mill Lane. It’s a public footpath in Halnaker (pronounced Ha’naker), a hamlet a few miles north of Chichester in West Sussex, in the South Downs National Park. The lane follows an ancient track along the route of Stane Street, the London to Chichester Roman road. Over the years many have walked along this route forming a hollow way, where the path has sunk down, worn away by centuries of footfall. A magical tunnel of trees!