Why did Ann Clwyd get such an easy ride during her appearance at the Chilcot inquiry this week, from both m'luds and the media? Clwyd is at least as complicit as her former boss Tony Blair in the dissemination of tall tales designed to justify the attack on Iraq.

Clwyd is Labour MP for Cynon Valley and head of Indict, a group that campaigned for many years for the arrest and punishment of Saddam Hussein and his cronies under international law. On the eve of the Iraq War – 18 March 2003 to be precise – Clwyd wrote an article for the Times in which she claimed that Saddam had a people-shredding machine.

Apparently the Ba'athists would dump their opponents into a machine "designed for shredding plastic", and later put their minced remains into "plastic bags" so they could eventually be used as "fish food".

It gets worse: apparently these unfortunate men were put into the shredder feet first so that they could briefly behold their own mutilation before death.

Not surprisingly, Clwyd's shocking claims spread around the world like a virus. The then prime minister of Australia, John Howard, talked of Saddam's "human-shredding machine" in a speech justifying his decision to send troops to Iraq. Paul Wolfowitz, the Bush administration's hawkish deputy defence secretary, expressed his admiration for Clwyd's article and a link to it was posted on the US state department's website. Numerous pro-war journalists repeated Clwyd's claims.

There was only one problem: there was no strong evidence, and there still isn't, that Saddam had anything like a people-shredding machine.

When I investigated this story for the Spectator and the Guardian in early 2004, I found no convincing evidence that such a medieval-sounding contraption ever existed.

It seems Clwyd based her story on the uncorroborated claims of one individual from northern Iraq. Neither Amnesty International nor Human Rights Watch, in their numerous investigations into human rights abuses in Iraq, had ever heard anyone talk of a human-shredding machine.

Worst of all for Clwyd, I interviewed one of the Iraqi doctors whose grisly job was to examine the bodies of executed prisoners at Abu Ghraib, where the shredder was allegedly based, and he said no prisoner was ever killed by being shredded. And for the record, he really hated the Ba'athist regime.

It's worth remembering the role that Clwyd's claims played back in mid-March 2003. There was widespread opposition to the war, as evidenced by the million-strong march in Hyde Park in February 2003.

People were already asking questions about the "dodgy dossier" and Blair's claims about WMD. The story of the shredder seemed designed to jolt us all out of our stupidity and convince us to back the government's war against evil. As the headline on Clwyd's article in the Times put it: "See men shredded, then say you don't back war."

The shredder story was used in a last-ditch effort to change people's minds. As Trevor Kavanagh at the Sun rather wishfully argued: "British resistance to war changed when we learned how sadist Saddam … fed dissidents feet first into industrial shredders." If Blair's dodgy dossier was cynically used to drum up support in the run-up to the invasion, then Clwyd's shredder story was cynically used to batter the last bit of war-scepticism out of the British public.

And yet Clwyd has not been subjected to anything like the same level of media criticism as Blair has been. This points to a problem with the way we remember the Iraq war. In the mythical version of events that is being promoted by the media off the back of the Chilcot inquiry, Blair, and his evil sidekick Alastair Campbell, single-handedly duped the cabinet, parliament, the media and some of the public into supporting the war.

The truth is that it wasn't only Blair who was spreading tall tales, and much of the media wasn't nearly as critical as it should have been of the Bush/Blair drive to war. Clwyd's appearance at the Chilcot inquiry was an opportunity to remind ourselves that Blair was not a superhuman warper of rational-mindedness and that the Iraq-related hysteria spread far beyond his coterie of advisers. Unfortunately, we've wasted this opportunity.