Blair returns to centre stage for Iraq inquiry

For many of those watching – either in the inquiry room or via the media – there will be a hope that it finally marks a moment of reckoning for the former prime minister, right.

For Mr Blair himself it will be a chance to publicly justify what was undoubtedly the most contentious decision of his premiership, one which has come to define his political legacy. He will be the star witness when the inquiry turns to the politicians, having so far heard from a succession of diplomats, officials and military top brass.

The picture they have painted is one of concern within Whitehall at both the legality and the wider political legitimacy of military action to oust Saddam Hussein, combined with a lack of planning for the aftermath.

Mr Blair will, no doubt, face questions about whether he could have used his leverage as America's key ally to ensure that more was done to prevent Iraq spiralling into chaos following the invasion.

But the main issue will be the central decision to go to war in the first place and whether he took the country into conflict on the basis of a "lie" regarding Saddam's alleged weapons of mass destruction.