SOME will always believe that Tony Blair took the country to war in Iraq on a lie, but the most damning charge emerging from the Chilcot inquiry into the Iraq war in London so far is Britain went to war on a wing and a prayer.

The main charges, after four weeks of cross examination, are that Britain had minimal influence over American diplomatic and military strategy, did not plan correctly for the aftermath of war, and utterly misconstrued post-war Iraqi society.

It is these charges as much as whether intelligence was doctored that are likely to make the Labour political class squirm when they give evidence to the inquiry starting in January. The chronology to disaster that has seeped from the inquiry makes sometimes shocking reading. It is after all the first time the British diplomatic and military establishment have had to discuss openly their secretive relationship with the US in the run-up to the war.

The diplomats have been freed to disclose their distaste for the simplicities of the neo-cons in Washington, their limited entry points into Washington bureaucratic in-fighting and their shuffling admission that they went to war knowing the aftermath was unplanned — a “known unknown” in the immortal words of US Defence Secretary Donald Rumsfeld, one of the villains of this inquiry so far.

Yet what has emerged already from the 12 sessions with British defence, intelligence and diplomatic officials is the extent to which Britain seemed to slide into war, ultimately with little Whitehall (UK civil service) resistance. The inquiry has also shown the extent to which Whitehall went to war ignorant of Iraq's near economic collapse, or the risks of a Sunni-Shia civil war.

On the basis of the evidence given so far, these are the key questions the political class will have to answer

— Did Tony Blair and the cabinet gradually commit to regime change in Iraq and did they always know they would join the war if UN support was not forthcoming?

Almost all the evidence from the military insists that British joint planning with the Americans was contingent on political endorsement, and the backing of the UN. Yet former ambassador Sir Christopher Meyer claims Blair committed himself intellectually to regime change.

— Did Blair give the defence ministry conditional permission to prepare for war at a secret meeting the weekend prior to meet George Bush at his ranch in Crawford in April 2002?

— Should Britain in March 2003 have withdrawn its support for the war after the failure to secure a second UN resolution giving Saddam a final chance to comply?

Edward Chaplin, the UK Foreign Office's director for the Middle East, claimed he persistently flagged up that an invasion without UN support would lack legitimacy, as opposed to being unlawful.

— Did Britain plan for the aftermath properly? Lt Gen Freddie Viggers, the chief British military representative in Baghdad after the war, told the inquiry “We suffered from the lack of any real understanding of the state of that country post-invasion.”

— The Guardian, London