The BBC has a tape of David Kelly expressing serious concern about how the British prime minister's No. 10 Downing Street office made the case for war against Iraq.
Susan Watts, science editor of the TV current affairs program Newsnight, recorded her conversations with the weapons expert, who killed himself last week.
In her report she quoted a "source" -- now known to be Kelly -- suggesting that No. 10 was "desperate" for information and had exaggerated "out of all proportion" the claim that Iraq could launch weapons of mass destruction within 45 minutes.
The BBC believes the tape is the "smoking gun" that will exonerate Andrew Gilligan, the Today program correspondent who originally reported the suggestion that No. 10 included the 45-minute claim in its September dossier on the case for war "to make it sexier", against the wishes of the intelligence community.
Gilligan did not mention the Downing Street director of communications, Alastair Campbell, until a later Mail on Sunday article.
The tape's existence explains the corporation's determination to stick by its story under the onslaught of criticism from No. 10. The BBC will submit the tape to the judicial inquiry led by Lord Hutton and will tell him that Watts and Gilligan checked their quotes with Kelly before broadcasting them.
In Watts's report on June 2, an actor speaks her source's words, saying of the 45 minutes claim: "It was a statement that was made and it just got out of all proportion. They were desperate for information, they were pushing hard for information which could be released. That was one that popped up and it was seized on and it's unfortunate that it was.
"That's why there is the argument between the intelligence services and the Cabinet Office/No. 10 -- because they picked up on it and once they've picked up on it, you can't pull it back from them."
Kelly told the foreign affairs select committee that he did not believe he was the main source of Gilligan's story but later told the former BBC journalist Tom Mangold that he was. The existence of the tape, and the admission to Mangold, suggests that Kelly, who has been described by friends as honest and decent, could have been deeply worried about whether he had told the full story to the committee.