Graffiti Action!
The skill people at Bristle have produced a book documenting political street expressions in Bristol & the South West from 1998-2005. Its a top read and a bargin for £6! You can buy online from:

http://www.fugazi.net/dswat/catalog/product_info.php?products_id=922

PS. I love this bit on thier press release; There is also explanatory information relating to subvertising, publicity sabotage, etc. These and other articles are published purely to document a living history, and never to encourage direct action. Oh no.

Oh no indeed.