Murdoch described Cameron as a "good family man," because he noticed at a social gathering that the British leader took good care of his young son.
Murdoch was less flattering about Cameron's predecessor, Gordon Brown, describing him as an unbalanced man who pledged "to make war" on News Corp. when Murdoch said his papers would call for a change of government at the next election.
"I said, 'I'm sorry about that, Gordon, thank you for calling.' End of subject," Murdoch told the court. Brown issued a denial of that conversation to the BBC.
Murdoch is to take the stand again Thursday, probably to answer more questions on the phone-hacking scandal and News Corp.'s bid for control of BSkyB.
This is the second time in nine months that he has faced a public grilling in Britain. In July, he and James were called to give evidence before a parliamentary committee.
Despite the hacking scandal that has damaged both his media empire and his reputation, Murdoch said he remains a lover of newspapers and summed up his journalistic mission this way in court Wednesday:
"Always to tell the truth, certainly to interest the public, to get their attention, but always to tell the truth.... I have great respect for the British public, and I try to carry that through."
Whether the British public reciprocates that respect is now being sorely tested.