O ver four years in the 1820s, Charles Waterton built a 9ft-high, 3-mile-long wall around the parkland and lake of Walton Hall. The fox- and poacher-proof boundary enclosed what could be the world’s first nature reserve, completed in Yorkshire 200 years ago. Waterton, an eccentric, controversial and pioneering environmentalist, built nest boxes, special banks for sand martins and innovative bird hides, and offered local people sixpence for every hedgehog they brought into his reserve. After completing the wall and banning hunting and shooting, he recorded 5,000 wildfowl on his lake and 123 species of birds, including ones that were widely persecuted at the time, such as herons and kestrels. Droves of hedgehogs and so-called vermin, such as weasels, were said to gambol freely like rabbits through his reserve.…