We throw away mountains of plastic. More than three and a half million tonnes of it, chucked out by Britons every year, clogging up landfill and polluting the seas. Now one supermarket chain, Iceland, has promised to turn all its own brand goods plastic-free by 2023. And Europe wants to make all plastic packaging recyclable or reusable by the end of the next decade. But how far are retailers prepared to go and will recyclers be able to follow?