Iraq: just how did it happen?

For, while Tony Blair's former communications director spoke about the Government's efforts to seek a diplomatic solution, the problem is that people struggle to differentiate between the "spin" and the facts.

Equally, Mr Campbell's assertions that the UK and US did take adequate steps to plan for the invasion's aftermath. If they did – and, again, Keighley-raised Mr Campbell has to be taken at his word – it did not work.

Apart from confirming that Gordon Brown was a key member of the "inner circle" involved in decision-making on Iraq, despite his attempts to distance himself from the war, yesterday's session revealed the extent to which the Government sought to manipulate public opinion.

Not only was Mr Campbell given unprecedented access to classified security intelligence, which ran counter to previous convention, but Mr Blair became exasperated that this material could not be put into the public domain.

This culminated with the publication of the so-called "Dodgy Dossier". Mr Campbell's defence was that this was "an exercise of openness" because his boss was frustrated at being repeatedly asked the same questions about the war's justification.

Yet it was the manner that this data was used – and taken at face value – that proved so damaging. Rather than including clear caveats, Mr Campbell's handiwork – and chairing of key intelligence meetings,

again contrary to protocol – left the impression that Saddam not only had weapons of mass destruction, but that he could strike Western targets within 45 minutes.

If the Government believed it was taking the right course of action, it had no need to wildly exaggerate its case. The strength of argument would have been compelling.

The legacy is bloodshed in Iraq, and a breakdown of trust between the Government and the electorate because unelected officials, like Mr Campbell, far exceeded their legitimate authority.

The inquiry's task is to put in place measures to prevent these policy shortcuts ever happening again. It cannot afford to fail.