It is a puzzle. I know we're not the world's worst but we've always seemed to do worse than many of our European neighbours, almost as though littering is baked into the British psyche, though I'm at a loss to know why that should be. Perhaps WW2 turned us into a nation of obsessive hoarders and the 50s/60s became a backlash of obsessive thrower-outers - there might be something in that, but it doesn't explain why the throwing out can't be into bins as opposed to 'just anywhere'.