Public Pressure: Ashcroft, 61, started an online petition asking Walkers, the UK’s biggest crisp brand, to recycle its used packets. Activists turned up the heat by encouraging people to mail empty packets directly to Walkers. Thousands did so, Ashcroft says.

Corporate Engagement: Within weeks, Walkers(33) announced a program to collect empty packets for recycling into plastic-aluminum pellets for use in outdoor applications like park benches. “It just shows that if enough people try hard enough, then these companies can be made to change their mind,” Ashcroft says.