Media mogul Rupert Murdoch has told the Leveson Inquiry that Labour leader Gordon Brown “declared war” on News Corp after the Sun moved to back the Conservatives in 2009.

Appearing before the inquiry today, Murdoch described a phone conversation between the pair, during which the veteran newspaper proprietor told the then Prime Minister that the newspaper would be backing a change of government in the next election.

Telling the court that he did not think Brown was in a “very balanced state of mind” during the call, Murdoch explained that the politician had called on the day of his party conference speech in 2009 after hearing about the paper’s altered political allegiance.

Murdoch said: “Mr Brown did call me and said ‘Rupert, do you know what’s going on here?’ I said ‘What do you mean?’ He said, ‘Well the Sun and what it’s doing.’ I said ‘I’m sorry to tell you Gordon, but we will support a change of government when there’s an election.’”

Despite suggestions from former Sun editor Kelvin MacKenzie that Brown “roared” at Murdoch for 20 minutes, Murdoch insisted that there were no raised voices during the conversation.

Describing his relationship with Brown to the court, Murdoch said: “My personal relationship with Brown was always warm — before he became Prime Minister and after. I regret that after the Sun came at him, that’s not so true but I only hope that can be repaired.”

But Murdoch added that Brown made a “totally outrageous statement” when he described News Corp as a “criminal organisation,” after alleging that his health records had been hacked.

“He said that we had hacked into his personal medical records when knew very well how the Sun had found out about his son which was very sad”, Murdoch told the court, who went on to explain that the story relating to Brown’s son’s Cystic Fibrosis had been obtained from a father in a similar situation.

To allegations that he traded favours with Tony Blair, Murdoch repeatedly denied the suggestion: “You are making inferences. I never asked Mr Blair for anything, and neither did I receive anything.”

The court heard that Murdoch was slow to endorse the Labour party in 1994, but he denied that that was part of a strategy to gauge commercial interests. Later in his testimony, somewhat losing his patience, Murdoch added to Robert Jay, QC: “I don’t know how many times I have to state to you Mr Jay, that I never let commercial considerations get in the way.”

After a 1994 dinner with Blair, Murdoch acknowledged that he may have said “He says all the right things but we’re not letting our pants down just yet”, but could not remember exactly.

Similarly, Murdoch did not recall speculating on the future of his relationship with Blair, when he reportedly said: “If our flirtation is ever consummated Tony we will make love like porcupines — very, very carefully.”

Turning to his relationship with David Cameron, Murdoch denied saying he “didn’t think much” of the Conservative party leader. He recalled meeting him at a family picnic at his daughter’s house, and was “extremely impressed by the kindness and feeling he showed to his children”.

When asked if he discussed issues such as broadcast regulation, BBC license fees or Ofcom, Murdoch denied the allegations. He said: “You keep inferring that endorsements were motivated by business motives. If that were the case we would always have supported the Tories, because they’re always more pro-business.”

Jay asked if he and Cameron discussed the appointment of ex-News of the World editor Andy Coulson as spin doctor for the Conservative party. Murdoch explained to the court that he “was as surprised as everybody else” by the appointment.

Murdoch denied rumours that he hadn’t forgiven David Cameron for calling the inquiry, explaining that the state of media in the UK is of “absolutely vital interest to all it’s citizens”, and adding that he welcomed the opportunity to appear before the court because he “wanted to put certain myths to bed.”

The billionaire newspaper owner was also asked about his relationships with numerous other politicians, including Scottish politician Alex Salmond and former Prime Minister John Major. Murdoch also told the court that he “remained a great admirer” of Margaret Thatcher, but denied that he was “one of the main powers behind the Thatcher throne.”

Murdoch echoes his son James’ testimony, saying that relationships between the media and politicans were “part of the democratic process”. He added: “Politicians go out of their way to impress people in the press. All politicians of all sides like to have their views known by the editors and publishers of newspapers, hoping they will be put across, hoping they will succeed in impressing people. That’s the game.”

At the start of today’s hearing, Lord Justice Leveson responded to the furore relating to emails from Jeremy Hunt revealed during James Murdoch’s testimony to the court yesterday.

“I am acutely aware from considerable experience that documents such as these cannot always be taken at face value and can frequently bare more than one evaluation. I am not taking sides or expressing opinion but it is very important to hear every side of the story. In due course we will hear all relevant evidence from all relevant people.”

Rupert Murdoch’s evidence to the inquiry will continue at 10am tomorrow.

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