The work of Andrew Gilligan lies at the heart of the Hutton inquiry. It was his report on BBC Radio 4's Today programme, claiming that the Government "sexed up" last September's Iraq weapons dossier, which was seized on for sustained attack by Downing Street. The death of Dr David Kelly came in the fallout from this bitter confrontation.

Since the scientist's death, and the bruising questioning he faced during the inquiry, Mr Gilligan has returned to work for the BBC, but not in his former post. He is on secondment, making radio documentaries while waiting for Lord Hutton to present his report.

In the final days before publication, Mr Gilligan, at one stage a desolate figure, is much more bullish. He had been turning down the requests for public engagements which had followed his recently acquired fame, or notoriety, but last week appeared at a dinner in front of a hundred guests to give a robust defence of his report and attack his bête noire Alastair Campbell. It is also a sign of his improving frame of mind that he has put back some of the two stones he lost due to the "Alastair Campbell diet", as he puts it, during the inquiry.

If the BBC does not return him to the Today programme or an equally senior frontline post, he will leave, firing a parting salvo at his bosses for caving in to Downing Street. This will also allow Mr Gilligan to write a book about his experience - something he has agreed not to do if he stays with the corporation - which may make him up to £ 250,000. On a longer term basis, the journalist has received an attractive job offer from a newspaper.

Mr Gilligan had been brought into Today by its then editor, Rod Liddle, from The Sunday Telegraph to bring in a more cutting edge from the print medium and "shake things up". The BBC head of news, Richard Sambrook, told the Hutton inquiry the feeling was that some of the occupants of the defence correspondent's post had been little more than MoD press officers.

The Today correspondent's style of reporting earned him hostility, not just within the Government, but also among some fellow BBC journalists.

Last week's Panorama special, which was highly critical of him and of the BBC management for backing him, is a salvo in that internecine conflict. The programme also showed an interview with Dr Kelly in which he appeared to contradict the Government's position on Iraq's supposed WMDs, including the "45-minute threat".

The interview took place on 29 October 2002, but Panorama chose not to show it during the months of confrontation with Downing Street when doing so would have helped the case of Mr Gilligan and the BBC in the public eye. Some within the corporation see this as deliberate sabotage.

The reporter's trouble with the Government began in 1999, soon after he joined the BBC, with a report suggesting that attempts to codify the various EU treaties amounted to a constitution for a European superstate. Downing Street attempted to dismiss him as "gullible Gilligan". His irritant quotient rose with further stories on the British forces' equipment failures during the Kosovo conflict, and on Geoff Hoon, the Secretary of State for Defence, going on holiday just before the Iraq war.

Mr Gilligan's report from Baghdad especially irked No 10, and "gullible Gilligan" became "Saddam's stooge". But, with widespread scepticism in the media over Tony Blair's justification for the invasion, this appeared to do the journalist little harm. Each time one of his reports led to a fierce rebuttal from Downing Street, went the joke among journalists in Baghdad, his salary went up by £5,000.

All that has now changed. With the government protagonist, Alastair Campbell, gone, there is a possibility that the BBC hierarchy may decide to sacrifice the journalist to draw a line under its conflict with Downing Street. The main charge against Mr Gilligan boils down to four words uttered on an unscripted radio broadcast at 6.07am on 29 May last year: "The Government probably knew" that the claim Saddam Hussein could launch his weapons of mass destruction within 45 minutes was wrong, but had pressed for it to be included in the dossier. In a subsequent article in The Mail on Sunday, for whom he was a regular contributor, the BBC reporter accused Alastair Campbell, Tony Blair's then director of communications, of being the instigator of this "sexing up" operation.

Mr Gilligan's notes from his meeting with Dr Kelly, at the Charing Cross Hotel in central London, taken down on a palmtop computer, disclosed at the Hutton inquiry, did not reflect what Dr Kelly allegedly said to him. A further charge against Mr Gilligan is that he sent e-mails to members of the Commons Foreign Affairs select committee, in effect disclosing that Dr Kelly was also the source of a report by Susan Watts, the science editor of BBC2's Newsnight programme, about weapons of mass destruction.

Mr Gilligan's defence is that he did not repeat the four words, which he admitted to Lord Hutton were "imperfect", in subsequent broadcasts. Alastair Campbell's suspected culpability, Lord Hutton heard, was something Dr Kelly had also mentioned to Ms Watts.

The inquiry also heard that Mr Campbell had asked John Scarlett, the chairman of the Joint Intelligence Committee, tasked with drawing up the dossier, for no less than 15 changes to "harden up" the document. Mr Scarlett had acquiesced to many of them, including on the crucial issue of the 45-minutes threat.

Furthermore, what became clear during the hearing was that there was widespread disquiet within the intelligence community about claims made in the Iraq dossier. And Sir Richard Dearlove, the head of MI6, and Mr Scarlett both admitted that the 45-minute claim applied to battlefield weapons with limited range, and not long-range missiles, as the dossier had employed.

The Susan Watts episode was another example of the divisions within the BBC. She became the subject of some mirth when it was revealed that after hearing Mr Gilligan's Today broadcast, she telephoned Dr Kelly to ask "have I missed a trick?"

The Hutton inquiry heard a tape she made of a conversation she had with Dr Kelly, without his knowledge, in which he told her about the unease felt in the intelligence community about the dossier, and actually named Alastair Campbell. But she failed to use any of the material, considering it, she told the inquiry, "tittle tattle" and "gossip".

The science editor, cruelly nicknamed Susan "Watts-the-story" by some in the BBC, is on maternity leave with her fourth baby.

On the matter of outing Dr Kelly as Ms Watts's contact, Mr Gilligan offered an unreserved apology. His friends point out in mitigation that Downing Street was briefing tame Labour MPs on both the foreign affairs Committee and the intelligence and security committee against him, and he was attempting to balance the book.

So what can Lord Hutton's report hold for Mr Gilligan?

The worst case scenario: Lord Hutton could decide that Mr Gilligan totally misquoted Dr Kelly, and exonerates Tony Blair, Geoff Hoon and Alastair Campbell of any blame, either over the scientist's death, or the sexing-up of the dossier. Susan Watts becomes director general.

Such a report could, however, be to Mr Gilligan's advantage. Lord Hutton will face accusations of a whitewash. The BBC management will not allow Mr Gilligan to return to frontline reporting such as on the Today programme. Mr Gilligan can go off to write his book.

The mid-level scenario: Lord Hutton apportions some blame to Mr Gilligan's reporting. But others are criticised as well. This will not be ideal for Mr Gilligan. He is unlikely to be allowed to return to the Today programme. The deal he has made with the BBC management also means that he will not write a book while he is in the corporation's employment, and new BBC regulations will, in the future, prevent its journalists from writing newspaper columns. Mr Gilligan will lose his chance of becoming a celebrity.

The best case scenario: Lord Hutton exonerates Mr Gilligan. He is welcomed back to the Today programme as editor designate. Rod Liddle rejoins the BBC as heir apparent to director general Greg Dyke. Susan Watts is sacked for missing a huge story. But this scenario, most people familiar with the Hutton inquiry accept, is highly unlikely.