A fundamental security review is sure to ensue after a breath-taking breach which allowed a protestor to throw powder at Tony Blair during Prime Minister's Questions.

Despite the anti-blast blocks and armed police that surround the Palace of Westminster, the attack has highlighted how easily a lone terrorist carrying a vial of anthrax or sarin can get around the most sophisticated security measures and cause havoc and panic -- not just in the House of Commons but in any crowded public place in the world.

It was a bloody good shot, though.