"What's the point of walking when you've got cars?" John Swallow plays devil's advocate for a news report about the rambles available along the Manifold Valley - although when the admitted 'townie' struggles to recognise a Friesian cow you begin to wonder if he really is out of his element. Julian Plowright is Swallow's guide for a wander along the Staffordshire and Derbyshire border in the Peak District National Park.