Ministers in the last Labour government were constantly mindful of how their actions would be portrayed by Rupert Murdoch's newspapers, the party's deputy chairman Tom Watson said today.
Mr Watson told the Leveson Inquiry that during his time as a minister under Mr Brown there were frequent conversations about how something would "play out in The Sun".
The MP, one of Mr Murdoch's fiercest critics over the phone-hacking scandal, became a junior minister at the Ministry of Defence in 2006, later moving to the Cabinet Office.
In his written evidence to the inquiry, he said: "I have no direct experience nor knowledge of the offer of favourable treatment in return for political support, yet I have never met a minister who didn't know the corporate aims of Rupert Murdoch."
Addressing the inquiry in person today, Mr Watson said the News International newspapers were "the ones that had the connections and everyone was aware of it".
"As a minister when I discussed issues and policy there was always a conversation about how this would play out in The Sun," he said.
"There was a sense that there was a mystique about the News International stable, that they had unique access to Downing Street, and as a minister that was important, and the way you were portrayed in News International papers was important and they factored that into their thinking."
He called for reforms to ensure the public can have confidence in ministers' relations with newspaper executives.
"I have no hard evidence there was a craven understanding between politicians and senior executives at News International, but I do believe that is the general view of the public and we need reforms that ensure public confidence in those relationships is restored," he said.
Mr Watson also told the inquiry that he had discovered evidence that the News of the World's so-called fake sheikh, Mazher Mahmood, had been responsible for putting him under surveillance during the Labour Party conference in 2009.
The MP said the newspaper thought - wrongly - that he was having an affair. He said the surveillance "was a mission by Mazher Mahmood".
Former home secretary Alan Johnson defended his decision not to refer the Metropolitan Police's handling of phone hacking to HM Inspectorate of Constabulary in 2009.
He stressed that he was given assurances by the police that the issue did not go beyond Clive Goodman and Glenn Mulcaire, who had been convicted, and that the New York Times' revelations and the Milly Dowler case had not yet come to light.
"I think at that stage deciding not to call in someone independently to examine it, I think it was a sound decision. I wish I had called them in, but..."
He said to have called in HMIC would have been "more than an implied criticism, it's an explicit criticism".
Mr Johnson said that he met former News International chief executive Rebekah Brooks when he was running for the deputy leadership of the Labour Party.
He said his team was "excited" about the meeting but he got off on the wrong foot by calling her by the wrong name.
"I shook her hand and said 'hello Rachel', and I don't think that went down very well, so it wasn't a good start," he said.
The Labour MP criticised the media's handling of complicated stories and the way that they were "personalised" in the newspapers.
"The Government need to get very important, sometimes complex, information across, but the slightest slip and it turns into something personal against the minister rather than an issue about the actual policy," he said.
Lord Smith, who as Chris Smith was culture secretary in Tony Blair's first term between 1997 and 2001, said he regretted not doing more to tackle the behaviour of the press at that time.
"I have to hold up my hands and say the changes we were able to secure (after the death of Diana, Princess of Wales) in 1997 lasted for a two or three year period in terms of their impact and effect, I regret that I didn't see properly at the time that this wasn't enough and we should have pushed further."
He said the then chairman of the Press Complaints Commission (PCC), Lord Wakeham, was "remarkably successful" in getting editors to agree to some reforms after the death of Diana, but acknowledged that they were "modest".
Lord Smith said he himself pressed unsuccessfully for a system of sanctions, a definition of the public interest and a more proactive approach by the PCC.
But he said he was "very anxious" to avoid legislation.
"For the two or three years following the Wakeham changes immediately after the death of Diana the conduct of the press did improve," he told the Leveson Inquiry.
"There was a palpable change of behaviour but after that two or three year period I think it began to slip and, as we know from all the evidence that you have been receiving it slipped grievously in quite a number of ways."
He added: "It's a matter of regret to me that I did not often enough return to the fray over the course of the following three years."