welcome to hardtalk. i'm stephen sackur, and today, i'm on the banks of the river lea, north of london. this beautiful habitat has, in recent years, become a battleground, which has pitted anglers and conservationists against the privatised water companies and the industry regulator. my guest today is the former punk rock star—turned—environmental campaigner feargal sharkey. now, he is leading the campaign to clean up britain's waterways. but can years of environmental degradation really be reversed? feargal sharkey, welcome to hardtalk.