Campbell, his 'mate' and a reputation in the dock

Tomorrow, more than a month after his first appearance at the Hutton inquiry, Alastair Campbell will return to Court 73 at the Royal Courts of Justice in London. On Tuesday Downing Street's outgoing director of communications will be followed on to the witness stand by the man he has described as a "mate": John Scarlett, the MI6 official who heads the Joint Intelligence Committee.

Between them the two friends could hold Tony Blair's reputation in their hands. Since they last came before Lord Hutton, he has heard volumes of evidence which suggests that the Government's September 2002 dossier on Iraq's weapons of mass destruction, the keystone of its case for going to war this spring, was not the unadulterated product of the intelligence agencies, as was claimed at the time.

Mr Campbell's assertion of 19 August that he had "no input, output [or] influence" on the dossier has been called into question many times since, even if the charge reported by the BBC journalist Andrew Gilligan - that he personally intervened to insert the dossier's claim that Iraq had weapons of mass destruction ready for use within 45 minutes - has not stood up. The inquiry has disclosed a torrent of Downing Street comment on Mr Scarlett's drafts of the dossier, including a letter from Mr Campbell to the JIC chairman which more than once stresses the Prime Minister's close interest in the process.

And the more Mr Scarlett denies that this had any influence on him, the more he will have to explain why so many of the claims made in the dossier have failed to pass muster. It is beginning to appear that Mr Campbell did not need to "sex up" the document, as the WMD expert, Dr David Kelly, is alleged to have told Mr Gilligan: he could rely on the JIC chairman to do it for him.

The apparent suicide of Dr Kelly, who found himself in the centre of a storm between the Government and the BBC, is what led to the Hutton inquiry. But last week the inquiry's senior counsel, James Dingemans QC, made it clear that the dossier would be as closely scrutinised as the circumstances surrounding the scientist's death, and with the start of cross-examination by Mr Dingemans and other inquisitors, the atmosphere has become far more brutal.

Fierce questioning by the BBC's counsel, Andrew Caldecott QC, brought out, for example, that a formal complaint about the dossier by a senior Ministry of Defence intelligence analyst, Dr Brian Jones, was never seen by the Joint Intelligence Committee or the parliamentary Intelligence and Security Committee. Dr Jones told the inquiry earlier that he suspected there had never been a formal JIC meeting to approve the final dossier, and he was proved right. Testifying over a clanking voice link, the head of MI6, Sir Richard Dearlove, confirmed that it had been cleared by a "silence procedure": if nobody objected, it was assumed that they were "content", to use a favourite Civil Service term.

Sir Richard quickly put Mr Dingemans right when he referred to the 45-minute "claim", as almost everyone has done throughout the inquiry. "I would prefer to refer to it as a piece of well-sourced intelligence," he said, ignoring the issue of its accuracy - if WMD had been so readily available, they would have been found by now. Nor was Britain's chief spy put out, as Dr Jones and some other MoD analysts were, by the fact that it came from a single source. "CX reports as produced by my service are essentially single source; and much high-quality intelligence which is factual or proved to be factual is single-source material," he said from his undisclosed location.

But the MI6 head did concede that the 45-minute report had been "misleading". Asked by Lord Hutton to elaborate, he said: "Well, I think the original report referred to chemical and biological munitions, and that was taken to refer to battlefield weapons. I think what subsequently happened in the reporting was that it was taken that the 45 minutes applied ... to weapons of a longer range."

Sir Richard was right. The original intelligence assessments of the dossier speak of chemical and biological "munitions", which Dr Jones earlier said he would "struggle" to describe as WMD. Yet Mr Scarlett never used the word "munitions" in his drafts of the dossier. On 10 September 2002, a day after the final intelligence assessment was produced, there is one reference to "weapons of mass destruction" being available within 45 minutes.

The point was immediately picked up in Tony Blair's foreword to the dossier, drafted by Mr Campbell and approved by the JIC chief. The dossier, said the Prime Minister, "discloses that [Saddam's] military planning allows for some of the WMD to be ready within 45 minutes of an order to use them". This reference remained unchanged in the final dossier, although in the rest of the document, no doubt as a result of comment within the intelligence community, Mr Scarlett was back to talking of "chemical and biological weapons".

Also in the draft foreword, Mr Blair says: "The case I make is not that Saddam could launch a nuclear attack on London or another part of the UK (he could not)." This did not appear in the published dossier, helping to bring about headlines such as the London Evening Standard's "ATTACK IN 45 MINUTES".

The Hutton inquiry has concentrated on the 45-minute question because it was the one raised by Dr Kelly, but much of the rest of the dossier has been discredited, including the claim that Iraq sought to buy uranium in Africa. As recently as last week it became clear that the lurid figures for deadly substances such as anthrax and VX nerve agent mostly resulted from book-keeping discrepancies.

As the hearings went into their second phase at the beginning of last week, Mr Dingemans outlined 15 questions "your Lordship may wish to consider". First on the list was: "How was the dossier of 24 September 2002 prepared, and who was responsible for drafting it?"

Within the first half-dozen were two more which should ensure the most searching cross-examination of Messrs Campbell and Scarlett: "Were the Prime Minister, Mr Campbell and other officials in No 10 Downing Street responsible for intelligence being set out in the dossier which was incorrect or misleading, or to which improper emphasis was given?" And: "Whether or not Mr Gilligan accurately reported what was said by Dr Kelly to him in his broadcasts on 29 May and in his Mail on Sunday article on 1 June 2003."

It has already been conceded that Dr Kelly was right about the 45-minute intelligence coming in late, and that it came from a single source. There has been no evidence that it was inserted into the dossier by Mr Campbell, but we have learned that while the heads of the intelligence agencies were content to fall in with Downing Street's wishes, at least some of their subordinates were deeply unhappy with the process.

The question at the root of the matter, the one that has severely eroded trust in Tony Blair, is: why was the dossier which took us into war so wrong? This week we may get some answers.