Former News International chief executive Rebekah Brooks spoke of her embarrassment today at turning down the exclusive story on the MPs' expenses scandal.
Brooks, 45, told the phone hacking trial at the Old Bailey that "in terms of errors of judgment" it was "quite high on my list".
She also described being summoned to Downing Street over information leaked by a public official about Saddam Hussein's plot to launch an anthrax attack on Britain.
Former Sun editor Brooks said her news team approached her about the MPs expenses "fraud" in spring 2009 - a month before the Daily Telegraph broke the story.
She said: "My news team came to me to tell me they had heard the unredacted information, to do with MPs' expenses - for want of a better word, fraud - could be available.
"It was going to cost quite a lot of money.
"In terms of errors of judgment, probably quite high on my list.
"I thought about it for too long.
"Days would go by and I thought, 'absolutely go for it', then I would change my mind.
"I drove my news team crazy with my indecision.
"I should have gone ahead.
"At the time I remember it being an incredibly high price."
Brooks, of Churchill, Oxfordshire, said the Telegraph did a "brilliant job" with the story.
She added: "It was quite embarrassing we didn't get it."
Brooks, who denies conspiring to hack phones, conspiring to commit misconduct in public office and conspiring to cover up evidence to pervert the course of justice, went into the witness box for her sixth day of evidence.
Brooks told the court that she authorised a payment to a public official for leaked information about a plan by former Iraqi dictator Saddam to smuggle anthrax into the UK for possible attacks.
She told the court she was deputy editor of the Sun in 1998 when the newsroom was contacted by someone alleging a "cover-up" by the security services over the alleged terror plot.
"It was very quickly brought to my attention this was a public official and he was asking for money for information," she said.
Brooks said that, after discussions with senior journalists about the validity of the information, she authorised a journalist to "enter into an agreement with the public official if the story turned out to be true".
"In the overwhelming public interest, this was absolutely the case," she said.
Brooks said she was called to a meeting at Downing Street with representatives from MI5, MI6 and GCHQ before the story had been published.
"They tried to encourage us not to publish," she said.
"It was a very brief discussion.
"The public had a right to know."
Brooks said she agreed not to publish information which would endanger the lives of any operatives in the field.
"When I got back I authorised money to go to the public official," she said.
The Sun ran the story and a chief petty officer was subsequently prosecuted for leaking the information after his identity was revealed, the court heard.