Parents everywhere will understand the desperation a father must feel if he is denied access to his children. It's not surprising some dads will go to extreme lengths, but is throwing powder at Tony Blair an effective tactic to win support?
Liberal Democrat MP Lembit Opik thinks not. "This is the way to destroy the credibility of your organisation," he said. Even Greenpeace, those doyens of direct action, thought it was a bridge too far, and regarded the throwing of an object as "too aggressive".
But protester Ron Davis had already tried talking to Tony Blair on a radio phone-in earlier this year. He didn't find it effective, and desperate people resort to desperate measures. However, as with any cause-related marketing idea, any direct action must, above all else, be relevant to the cause in order to win over the target audience. In this instance, that audience is the voting public and MPs.
As a stunt, it wasn't 'clever' enough to really win hearts. Apart from its use of the colour purple, the international colour of equality, there was nothing to link the action to the cause. And by mimicking the actions of terrorists, Fathers4Justice has potentially alienated its audience and extended the barriers between people and politicians.
Yet, 12 months ago, few people had heard of Fathers4Justice - now there are few that haven't. They got front-page coverage on every national newspaper. Anti-nuclear group Trident Ploughshares reckons it was "an extremely effective action, because it has opened up the debate".
In isolation, activities like this rarely achieve change. They need to be part of a wider campaign with at least an element of engagement and persuasion. However, it must be remembered that Fathers4Justice are not professional campaigners, merely dads driven to distraction by women and laws that don't let them see their kids.