I encourage young park picnic people to gather their litter before nightfall while they can still see where it all is - some give me lip, but others are very reassuring. I'm not sure it always achieves my objectives, but it is worth a try. I talk to any I see peeing in the bushes or smoking dope as well. A little seed of an idea might start them thinking..... Is that the sort of park use you are recording?
yes that's exactly the kind of thing I'm interested in, it's a pity I didn't speak to you two years ago! I'm in the final stages now of writing it all up as a phd, it's generally about the different ways in which the message that someone is caring for the space is gotten across to people and what impact it has. When I've been up to St. Andrews (I live in Bedminster) we've tried to do similar things with making the kids from the college aware of the litter problem without being heavy handed, it does seem to be particularly bad there.
Best of luck with your PHD Sam - did you come to any useful conclusions about shaping a different approach to the issues?