The real question is what is the point of this inquiry? Bagehot reckons that the testimony of officials might, might, disclose new information. Can it? The terms of the remit, the development and implementation of British policy, are well established. As Sir John put it in his opening remarks, “The findings of previous investigations have eased our task in finding relevant material.” Gary Gibbon reports that the former head of the FCO’s Mid-East section Sir William Patey testified that military action was considered the worst option in 2001. The aim of Chilcot’s investigation is to determine how and why this changed, but the answer is known: flawed intelligence preceded or proceeded Downing Street’s hardening attitude. Testimony from officials is unlikely to reveal which aspect of that dichotomy is accurate, something only Blair, his intimates and, if Blair told Him, God can answer.
The inquiry will decide whether the war was illegal but will not hand down a legally binding judgement - the inquiry enjoys none of the privileges of a court and no lawyers or judges are deliberating. Another unenforceable opinion on the causes of the Iraq war will not provide closure for any party.
PS: Open testimony may disclose new information on Gordon Brown’s role in decision making, which remains an unknown quantity.