John Cherrington and his seventy-four year old walking companion set out one fine morning in May to traverse the only English footpath that cuts south through the rural heart of the country, a formidable path called the Macmillan Way. Cherrington’s walking partner is Karl Yzerman, an irascible “bull of the woods”, a full twenty years his senior and the perfect foil to the wry and self-deprecating author. Their journey begins at Boston on the Wash and takes them...