The placards are apparently a "breach of Mr Haw's demonstration condition" since the Court of Appeal overturned the ruling that allowed Haw to demonstrate outside Parliament despite the Serious Organised Crime and Police Act 2005 (aka 'the Haw Law') which outlaws unauthorised protests within a 1km zone of Parliament Square.
Haw is quoted as saying:
All of my personal belongings have been taken and dumped in a container along with nearly all the displays. They have completely destroyed all the expressions of people who opposed the war in Iraq. What gives them the legal right to remove 40 metres of evidence of genocide and reduce it to just three metres?"