Speaking to The Mirror, the singer insisted that celebrities needed to use their popularity and influence to help shape important decisions.
"If David Beckham had of spoken out about Iraq it wouldn't have happened, I honestly believe that hand on heart, or Britain certainly wouldn't have got involved," he explained.
"Beckham's cultural gravitas was as such in that period that if he'd have gone, 'I don't want this war in Iraq, it's an awful thing, we should not do it', it wouldn't have happened, the public would've gone mad against it.
"But because he kept his gob shut, and everybody else did, it happened, we sleepwalked our way there."
McClure also criticised the amount of coverage dedicated to celebrities like Jade Goody and Prince Harry's ex-girlfriend Chelsy Davy instead of topics such as casualties in Afghanistan.