Across the River Wolf and along several miles of muddy Devon lanes lies Derek Gow’s lair. Inside a crepuscular barn filled with a pungent aroma, an imposing, bearded Scot sits surrounded by his collection of animal skulls, stuffed beavers, taxidermied badgers and birds of prey. A distinctive stench wafts from the head of an ibex mounted on the wall. The barn is badged as an education centre but it would terrify some visitors.

This gothic scene reaches its climax when – bang! – a shot is fired nearby. Gow looks relaxed. “She’s not shooting anything,” he says of his neighbouring farmer. “It’s a gas gun, trying to scare a bunch of complacent geese.”

Gow, a former sheep farmer, has become one of the most remarkable figures in British conservation. After working in various zoos, he began captive-breeding water voles 25 years ago. Since then, working with conservation groups and landowners, he’s repopulated wetlands with 25,000 of the highly endangered mammal. The “vole room” on his rewilded farm still produces 1,000 each year.