He must face the Hutton inquiry and answer its questions with the openness and transparency on which he so prides himself. There may well be compelling ethical arguments for removing murderous dictators and, on occasion, supporting America in doing so. But the argument advanced by this government, and the legal justification for the war on Iraq was to pre-empt the imminent threat presented by WMD. As this newspaper highlights today, the dossier on Iraq's weapons capability was hardened up in the days before its publication in such a way that it did not reflect the views of senior experts - and that is further evidence that Dr Kelly was right.Dr Kelly's death and the conspicuous absence of weapons of mass destruction in Iraq have resulted in a lamentable loss of credibility for Tony Blair. Already, the inquiry has shown that Dr Kelly was right in stating that the threat of Iraq's weapons was hugely exaggerated.The Hutton inquiry, with its investigation into the death of Dr Kelly, began as a sideshow to the key issue - the reasons for the conflict in Iraq - but has already shed welcome light on Tony Blair's central justification for taking this country to war.

What is more valuable, however, is that the inquiry is confirming what those opposed to war in Iraq already believed to be the case: the Government seriously exaggerated the danger of weapons of mass destruction. One or other may be forced to fall on their swords.The value of what the Hutton inquiry is telling us about these pillars of the British establishment - the BBC, the Civil Service and Downing Street - cannot be underestimated. His disquiet will surely increase in the coming week when both Powell and Campbell are due to give evidence. As he learns of the proceedings from the comfort of his Barbados beach holiday, Blair must be increasingly unsettled as to how the inquiry's evidence is being perceived. A letter from Hoon's office about Dr Kelly testifying was copied to Blair's chief-of-staff, Jonathan Powell, and to Alastair Campbell.

Martin Howard, the MoD's deputy chief of intelligence, testified that he had seen high-level correspondence which said Tony Blair had ordered a second interview of Kelly. Even then his job may not be safe.It also emerged last week that Tony Blair and his Downing Street inner circle were intimately involved in the handling of Dr Kelly. When Hoon faces questioning by the Hutton inquiry this week, he will need to come up with very convincing arguments as to why he overruled Sir Kevin. It was Hoon who forced Dr Kelly to give public evidence to the select committee. He also resisted attempts by the Parliamentary Intelligence and Security Committee to question senior MoD officials. It emerged that Hoon overruled his permanent secretary, Sir Kevin Tebbit, who had sought to spare Dr Kelly the glare of public cross- examination before the Foreign Affairs Select Committee. The Secretary of State for Defence, Geoff Hoon, may not be so lucky.