Forced to accept that intensive farming on the heavy clay of their land at Knepp was economically unsustainable, Isabella Tree and her husband Charlie Burrell made a spectacular leap of faith: they decided to step back and let nature take over. Thanks to the introduction of free-roaming cattle, ponies, pigs and deer – proxies of the large animals that once roamed Britain – the 3,500 acre project has seen extraordinary increases in wildlife numbers and diversity in little over a decade.Extremely rare species, including turtle doves, nightingales, peregrine falcons, lesser spotted woodpeckers and purple emperor butterflies, are now breeding at Knepp, and populations of other species are rocketing. The Burrells’ degraded agricultural land has become a functioning ecosystem again, heaving with life – all by itself.