Known for her striking red curls and meteoric rise from junior employee to top editor at News of the World, Brooks said Cameron was a personal friend and a neighbor in the picturesque Cotswolds area of southern England.
After she quit in July due to the uproar over phone hacking, Brooks said she had received "indirect messages" of support — text messages sent by the aides of politicians, but relaying their personal thoughts — including from Cameron.
"I received some indirect messages from No. 10, No. 11, the Home Office and Foreign Office," Brooks said, referring to Cameron, Treasury chief George Osborne and other leading Cabinet members.
She agreed with inquiry lawyer Robert Jay that a message from Cameron had told her to "keep your head up" and expressed regret that he could not offer more support publicly, because of the political pressure he was under over the hacking scandal.
The message was "along those lines, I don't think they were the exact words," Brooks said.
Brooks said she and Cameron would trade texts at least once a week, or twice a week during busier periods such as Britain's 2010 national election.
"He would sign them off 'DC,'" said Brooks, who showed composure and flashes of humor as she testified. "Occasionally he would sign them off LOL, 'lots of love', until I told him it meant 'laugh out loud.'"
Brooks confirmed that she had discussed tabloid phone hacking with Cameron, including after toxic revelations that the News of the World had hacked murdered schoolgirl Milly Dowler's phone when she disappeared in 2002. The girl was later found dead.