Chris Packham is a national treasure. A naturalist, photographer and author, he's best known for bringing nature into our living rooms as host of The Really Wild Show, Springwatch, Autumnwatch and Winterwatch. He's also an environmental campaigner and an anti-hunting advocate who has been targeted by threats and arson for his views. Aaron Bastani talks to Chris about the messy politics of overpopulation, the intimidation he's faced as an activist, and what it will take to get British politicians to take climate change seriously.