make peace not war
This canvas by Banksy was part of Brian Haw's anti-war protest in Parliament Square. The placards once stretched the entire length of the square, but were removed in a police swoop on 23rd May 2006. He had kept a continuous vigil since June 2001.
Jan 07 - The protest has been reproduced in an installation by Mark Wallinger at Tate Britain, entitled "State Britain". Part of the Tate is within the 1km exclusion zone, and this has been demarcated by a line on the gallery's floor.
Another of the placards here