Dog mess is the litter we find most offensive. In Portsmouth, as part of a nationwide experiment, they have been putting up big glow-in-the-dark posters of staring eyes. It's hoped that making dog owners feel watched will encourage them to pick up their dog mess. The exclusive national results of the experiment, run by Keep Britain Tidy, are revealed on this programme. Margaret Mountford also meets Nadine Nash, who lost an eye to toxocariasis, a disease transmitted by contact with dog faeces. London's annual Pride march leaves more litter than any other event in the capital, after the Notting Hill Carnival. It's a big street party and, in one day, the crowd drops 30 tonnes of litter. We are with the clean-up team following the parade and they have to work against the clock to clean the streets before they are opened to traffic. Neptune's Army is a band of underwater litter pickers in Devon. Shots of them in action reveal the shocking state of the underwater environment, which is used as a dumping ground by litterers hoping the waves will hide evidence of their litter crimes. And in Croydon, the wardens who track and fine members of the public £75 for dropping a single cigarette end.