Mr. Murdoch hires editors who often share his philosophy — right of center, anti-big government, anti-European Union, pro-business — and focuses on his favorites. He cements these ties through what a former editor at one of Mr. Murdoch’s London broadsheets described as “weird, familial relationships,” in which Mr. Murdoch and his editors socialize frequently and attend one another’s weddings. “They go on holiday with him, they attend his conferences in Sun Valley,” the former editor said.

But if the News Corporation’s British and American broadsheets — The Times and The Sunday Times of London, and The Wall Street Journal — give him gravitas, his tabloids give him a platform to promote his political and business interests.

And they are where his heart lies. Former editors at The News of the World, new defunct, and The Sun say he called frequently, affecting casualness but conveying just the opposite with pointed questions and long, ominous silences. “We called it telephone terrorism,” Mr. Greenslade said. “You’d try to fill in the gaps, and when you’re gabbling you’re bound to make mistakes.”

Mr. Murdoch expects his tabloids to beat the competition with aggressive, intrusive reporting that results in splashy exclusives that expose sexual misbehavior or debunk the establishment line. It is this expectation, former editors and reporters say, that has pushed his tabloids’ editors into ever more adventurous news gathering practices.

None of the editors said Mr. Murdoch ordered them to use illegal phone hacking or other illegal methods to obtain information. But his enthusiasm for articles that generated mass sales at the newsstand and riled the political elite was legendary on Fleet Street. “What am I supposed to do, sit idly by and watch a paper go down the drain, simply because I’m not supposed to interfere?” he once said, speaking of The News of the World. “Rubbish!”

Mr. Murdoch has never hesitated to dress down editors at The Sun and The News of the World when they make mistakes, either of omission or commission. It has never been a secret that The Sun promotes his business interests by, for instance, denouncing the BBC, or writing favorably about BSkyB television programs or 20th Century Fox films. At The New York Post, former employees remember how Mr. Murdoch meddled in the coverage of his rival Conrad Black, then the owner of The Telegraph, during Mr. Black’s legal troubles.

Nor is it a secret that Mr. Murdoch’s tabloids enthusiastically promote the politicians he likes and denounce those he does not.