It was now that Dr Kelly began to feel uncomfortable.
Back in the office the following Monday, 30 June, Dr Kelly's colleagues were talking about the foreign affairs committee hearings. The turning point came when a colleague pointed to Mr Gilligan's claim that his source had said it was "30 per cent likely" that Iraq had a chemical weapons programme in the six months before the war, and that though it was "more likely" there were biological weapons, it would have been reduced "because you could not conceal a larger programme. The sanctions were actually quite effective; they did limit the programme." These were, the colleague noted, the precise phrases used by Dr Kelly in discussions with colleagues.
David Kelly realised the game was up. He confessed to his bosses that he might be the source for some of the information - but not all of it. And not the damaging detail on the "45-minute" claim. It was a high risk strategy, but being accused by someone else would have been worse. He might have been charged with violating the Official Secrets Act. His career was at risk. And so, possibly, a year from retirement, was his pension. They might prevent him from going to Iraq that weekend to join the Iraq Survey Group which was hunting for evidence of weapons of mass destruction.
Dr Kelly wrote that day, 30 June, to his immediate boss, and said he thought he might have been the source of some, but crucially not all, of the Gilligan story. His letter said he had met the BBC reporter whose description of his meeting with his source "in small part matches my interaction with him, especially my personal evaluation of Iraq's capability".
But that was all.
He wrote: "I can only conclude one of three things. Gilligan has considerably embellished my meeting with him; he has met with other individuals who truly were intimately associated with the dossier; or he has assembled comments from both multiple direct and indirect sources for his articles."
Almost as soon as the letter was received government ministers were briefed. Detailed discussions took place. On 4 July Dr Kelly was interviewed by his line manager and by Richard Hatfield, the personnel director of the MoD. According to the MoD, Dr Kelly was told to go away for the weekend and "think over his options". He returned to work on 7 July, to more questioning. That day, the foreign affairs committee pronounced that Alastair Campbell was not guilty of "sexing-up" the dossier.
Dr Kelly was told he would have to appear before the Commons Intelligence and Security Committee to discuss his meeting with Mr Gilligan. The meeting would be in camera and Dr Kelly was promised anonymity. But the MoD broke that understanding. Exactly who did is unclear. Lord Hutton will be quizzing, on that subject, Alastair Campbell, Geoff Hoon, Sir Kevin Tebbit, the MoD's most senior civil servant, Richard Hatfield, its personnel chief, and Pam Teare, its head of news. But whoever made the decision, what is clear is that the MoD fixed on a highly unusual strategy of agreeing to "confirm or deny" any guesses put to it by journalists.
On 8 July, Geoff Hoon wrote to Gavyn Davies, the chairman of the BBC, enclosing a statement which the MoD were going to issue that day saying that Mr Gilligan's mole had come forward. He was not to be named, but he was not a senior intelligence source nor was he involved in the preparation of the dossier, as the BBC had claimed. Mr Hoon offered to tell Mr Davies the name "in confidence, on the basis that you would then immediately confirm or deny that this is indeed Mr Gilligan's source". The BBC refused. The MoD issued the statement citing an anonymous official who believed he was Mr Gilligan's source for some of his report. The inference was that the rest was made up.
The emotional temperature rose higher. Tony Blair justified Downing Street's ferocious pursuit of the BBC on the grounds that Andrew Gilligan's allegations were just about "the most serious charge" anyone could level against a Prime Minister. On 9 July, Guto Harri, the BBC political correspondent, spoke of Tony Blair doing "some BBC-bashing."
That day the MoD personnel director wrote to Dr Kelly stating that his "behaviour had fallen well short of the standard he expected from a civil servant of his standing and experience", but that "it would not be appropriate to initiate formal disciplinary proceedings".
His punishment was to be different. The same day Downing Street and MoD officials began leaking details of Dr Kelly's career, designed to assist journalists to identify him. Twowere told Dr Kelly's name.
The pressure on Dr Kelly was growing. He was asked if he wanted to take his wife to Jersey, where a Foreign Office house would be made available. Dr Kelly declined.
On 10 July a number of newspapers named Dr David Kelly as the official behind the Gilligan story. They quoted government sources triumphantly insisting Dr Kelly was a middle-ranking official, not a "senior and credible source", and that he had no access to intelligence briefings - both claims are untrue. They said he had only provided some input for a background section on UN weapons inspections for the dossier, that he was not a member of the intelligence services, had not seen the key material relating to the "45-minute" claim, and was not in a position to know if Downing Street had wanted to "sex-up" the document.
The BBC countered that Dr Kelly was an "intelligence source" in the broadest sense because he knew a lot about Iraq's weapons of mass destruction and would have seen secret material. But the BBC still refused to confirm Dr Kelly as its source. That day Dr Kelly, who was holidaying in Cornwall, received a summons to appear before the foreign affairs and the intelligence and security select committees on 15 July.
His appearance at the foreign affairs committee was televised. There, he was read a transcript of the Susan Watts Newsnight interview and said: "I do not recognise those comments." Asked if he had had any conversations with Gavin Hewitt, he replied: "Not that I am aware of, no. I am pretty sure I have not." Questioned on whether he had been critical of Mr Campbell to Mr Gilligan he shifted uncomfortably in his seat and closed his eyes before saying: "I cannot recall using the name Campbell in that context, it does not sound like a thing that I would say."
At the end of the 176-question grilling the Labour-dominated committee concluded that Dr Kelly could not have been the BBC's main source. To many commentators Dr Kelly came across as uneasy and evasive; and we now know at least one of his answers was untrue.
The next day, 16 July, Dr Kelly gave evidence in private to the intelligence and security committee and then, friends and family have since revealed, went home to Oxfordshire, deeply upset and unhappy. Some reports said he felt he had been humiliated by the committee, others that he felt his MoD bosses had put him in an impossible position, others that he was uncomfortable at discrepancies in his testimony.
Something now seems to have snapped for David Kelly. Had he felt - or been told - his performance hadn't been good enough? Did he fear losing his job, or calculate that his family would do better financially if he died in service? Did he fear what Mr Gilligan might say when he reappeared before the foreign affairs committee that day? Might he have learned that the BBC had a tape of his conversation with Susan Watts?
Or might he have felt he had compromised his integrity? The Baha'i faith is strong on veracity; one of its scriptures says: "The individual must be educated to such a high degree that he would rather have his throat cut than tell a lie, or think it easier to be slashed with a sword or pierced with a spear than to utter calumny."
On the face of it everything seemed normal the next morning, 17 July. Dr Kelly, finished a report for the Foreign Office. And though he e-mailed a journalist on The New York Times and wrote of "dark actors" at work around him he sent up-beat e-mails to Alistair Hay, a fellow scientist, and Roger Kingdon. "Hopefully it will soon pass and I can get to Baghdad and get on with the real job," he wrote to Mr Hay. To Mr Kingdon, his co-religionist, he wrote: "I'm hopeful things will be calming down in a week or so and I'll be going back to Baghdad."
He never did. That afternoon at 3pm - almost the exact time Mr Gilligan was again before the foreign affairs committee - David Kelly left home, telling his wife he was going for a walk. He did not return.
Just before midnight his wife alerted the police, and the next morning, 18 July, at 9.20, police found his body at Harrowdown Hill, a few miles away from his home. A post-mortem found the cause of death was bleeding from wounds to his left wrist. The fact that several incisions had been made - and that his watch appeared to have been removed whilst blood was already flowing, together with the removal of his spectacles - suggested suicide, experts said.
Not everyone agreed. Some doctors pointed out that slashing one wrist was an unreliable method of suicide. The fact that four electrocardiogram electrode pads were found on his chest aroused some people to suggestions of murder, though cardiologists said, most likely, Dr Kelly had earlier been wearing a portable monitor to diagnose a possible heart problem.
Two days later, on 20 July, the story took a new twist. The BBC acknowledged that Dr Kelly had been the primary source of its reportr. Andrew Gilligan came under renewed fire. Even if it was true, as seemed clear from the supporting evidence of Susan Watts and Gavin Hewitt that Dr Kelly had strong views about the "45-minute" claim, Mr Gilligan had gone further. He had quoted his source as asserting that "the Government probably knew that the 45 minute figure was wrong even before it decided to put it in". Critics pronounced that "sexed-up" was a phrase more to the taste of Andrew Gilligan than David Kelly.
Mr Gilligan was further damned a week later by a leak of the unpublished transcript of evidence he had given to the foreign affairs committee on his second appearance, after which he had been publicly criticised by Donald Anderson, the chairman. It purported to show that Mr Gilligan had admitted that Dr Kelly had not actually said Mr Campbell had inserted the "45-minutes" claim, but that Mr Gilligan had "inferred" it from their conversation. Mr Gilligan denied this was what he had meant, but it seemed the pressure had now shifted primarily onto the BBC.
Yet the twists were not over. News then broke that Susan Watts' conversation with Dr Kelly had been recorded. Richard Sambrook, the corporation's director of news, was said to have smiled broadly after listening to it. Some insiders said Dr Kelly mentioned Mr Campbell there too. The BBC has refused to say, but has passed the tape to Lord Hutton. Then came an admission from the Ministry of Defence that documents relating to the Government's media strategy on Dr Kelly had almost been incinerated. Unofficial reports suggested the MoD police had been called by a security guard after a senior official was discovered hurriedly shredding material. To cap it all, on the eve of David Kelly's funeral, came the tasteless and preposterous attempt by a senior No 10 official, to suggest that Dr Kelly, the Government's foremost expert on chemical and biological weapons, was a "Walter Mitty" style fantasist.
Yesterday there was yet another turn. It was reported that a two weeks ago, before Dr Kelly's apparent suicide - Sir Kevin Tebbit, the permanent secretary at the Ministry of Defence, described the man as "eccentric and unreliable."
He even went so far as to circle the side of his head, a gesture suggesting madness. And he did so at a private dinner with James Robbins, the BBC's diplomatic editor.
The Hutton inquiry takes its first evidence today.
We'll see what remains, when the dust clears... for after all,
'It's a matter of trust'.