This blog contains excerpts and links to positive articles I find online on graffiti, murals, and legal walls. There is a lot of negative information available, police and community groups will often show up to a graffiti "discussion" with binders filled with unfavourable quotes and links on graffiti. Much of it is information on large American cities, so is not always relevant to your area. Much of it provided by other negative groups, such as graffiti removal firms, promoting eradication, stiffer fines, more patrols as the only solutions. I'm sure one attraction of these "packages" is they confirm the biases already there, but they also save time - to be honest local lobby groups and law enforcement don't much time or money to do extensive research on their own. I hope these links I've collected will help people to work on a more balanced approach.
This info is mainly from three Google alerts I run on those topics, I get a daily summary and then repost some in here, with comments added. I've more general info on graffiti, murals, and legal walls on my main blog, much of it under the graffiti category, or you can browse yourself for keywords via the search box on either of these blogs.
Feel free to comment or repost.