Rebekah Brooks has denied knowing anything about phone hacking while she was editor of the News of the World.
She was quizzed in the witness box at the Old Bailey about what she knew of private detective Glenn Mulcaire and his hacking activities under her leadership from May 2000 to January 2003.
Asked by her lawyer, Jonathan Laidlaw QC, if she had ever heard his name mentioned at the time, she said: "No."
She gave the same reply when Mr Laidlaw asked if she knew of his activities, saying: "We did have private detectives working at the NotW."
She claimed that solicitors and law firms used them more, but added: "It is common practice in Fleet Street."
Mr Laidlaw went on to ask about phone hacking, and if that had ever been drawn to her attention.
She replied: "No, not at all."
Brooks told how she was given the job of editor of the NotW out of the blue in 2000, having been deputy editor of the rival sister daily, The Sun.
She had been working on an infant internet project called Exclusive.com with Andy Coulson at the time and had no inkling of her impending promotion.
Brooks, 45, is accused of conspiring to hack phones, conspiring to commit misconduct on public office and conspiring to cover it up, perverting the course of justice.
As Brooks gave her evidence, co-defendant and former lover Coulson did not look up from the dock.
Earlier, one charge against Brooks, over an alleged conspiracy to pay public officials for a picture of Prince William in a bikini, was dropped.
Brooks said she had been given hardly any notice of her switch from deputy editor of The Sun to editor of the NotW in May 2000, but added that by that time she had gained experience from regularly editing The Sun.
She told the court she suggested to her boss, Les Hinton, that Coulson would be a good deputy for her.
"We had completely different strengths and he (Mr Hinton) thought that would be a good combination.
"Andy had, I think, always been at The Sun. I had come from a features background and Andy had come more from a news background.
"Although I enjoy football, Andy is a die-hard football fan and sports fan", she said, describing how sports played a huge part in both newspapers.
Brooks said Coulson had a lot of experience on a daily paper and had been showbiz editor on The Sun.
She told the court that several Fleet Street editors had come from previous roles as showbiz editors.
At the start of the trial, jurors heard that Brooks and Coulson, who is also facing charges of conspiracy to hack phones and conspiracy to commit misconduct in a public office, previously had an affair.
Asked what her focuses as editor were, Brooks described herself as " issue- driven", and said: "The things that really affected the readers were things that I got excited about."
Brooks went on to tell the court of the huge influx of material to the NotW newsroom.
She said there were between 170 and 180 staffers at the newspaper but also a constant flow of shift workers and freelance journalists providing stories.
The picture desk had a wire crammed with images from agencies all over the world.
And the news operation could draw on copy from agencies like the Press Association and Associated Press, she said.
Brooks is accused of conspiring to hack phones, along with Coulson and former managing editor of the News of the World Stuart Kuttner.
She said: "When I was made editor he said 'You're my 17th editor, my dear' - that was how long he'd been there. Stuart, for me, had been there forever. He had an incredibly good reputation. I wouldn't say we were ever friends; he was a different generation and a different world almost. He was incredibly professional and respectful."
Brooks said that while Kuttner was mainly concerned with balancing the newspaper's budget as managing editor, he still had good contacts and would "dip in" to editorial matters, for example, a campaign for provisions to alert the public about paedophiles living in their area following the murder of Sarah Payne.
"Stuart - particularly after Sarah's law- Stuart would go out and give public statements on it. He still had very good contacts in lots of areas."
She described Kuttner as "incredibly hard-working and very diligent and very respected by Les Hinton, the CFO and directors".
Kuttner, as managing editor, was responsible for dividing the budget into weekly spending limits for department heads, Brooks said.
She said if it was likely that a large payment would "blow" that budget, approval would have to be sought from the editor.
The managing editor would have to know the spending had been signed off by the editor before approving it too, she said.
Brooks told the jury she brought former NotW news editor Greg Miskiw back from a new job in New York after just a week because she thought the post was "a waste of money".
Instead she made him lead a news investigations unit at the tabloid.
Describing their relationship, she said: "He was very old school and had been there forever... that's what it felt like to me. He ran quite a tight ship. People who worked with him said he was professional and hardworking, and worked long hours.
"I really only spoke to him in the course of our work. I didn't socialise with him, I didn't know that much about him personally.
"He was quite insular, he had an air of mystery."
The jury has already been told that Miskiw has admitted conspiring to access voicemails illegally.
Jurors heard that the investigations unit was dubbed the "dark arts department", alluding to alleged illegal activity.
Brooks denied this, and said: "The investigations unit, I think, did some great stuff while I was there. I don't recognise that description."