Former Sun and News of the World editor and Chipping Norton resident, Rebekah Brooks, is expected to lift the lid on her close relationship with the Prime Minister in evidence to the Leveson Inquiry.
David Cameron is said to have texted Mrs Brooks, telling her to "keep her head up" after she resigned from News International last July. It has also been claimed that the 43-year-old former editor sent Mr Cameron more than 12 text messages a day.
After her editorships Mrs Brooks, from Chipping Norton in Oxfordshire, went on to become chief executive of Rupert Murdoch's UK newspapers division News International in September 2009 until she resigned in the wake of the hacking scandal last July.
She and racehorse trainer husband Charlie are key members of the influential Chipping Norton set, which also includes Mr Cameron and his wife Samantha, Top Gear presenter Jeremy Clarkson, and Mr Murdoch's daughter Elisabeth and her PR guru husband Matthew Freud.
The inquiry has already heard that Mrs Brooks regularly met Mr Cameron and other top politicians along with Rupert and James Murdoch.
She hosted a Christmas dinner on December 23 2010, just two days after Business Secretary Vince Cable was stripped of his responsibility for media takeovers for saying he had "declared war" on the Murdochs' News Corporation empire. Mrs Brooks's wedding on June 13 2009 was attended by Mr Cameron and former prime minister Gordon Brown, and in March Mr Cameron was forced to admit that he rode a retired police horse loaned to Mrs Brooks by Scotland Yard from 2008 to 2010.
An updated biography of Cameron: Practically A Conservative, claims he told Mrs Brooks she would get through her difficulties just days before she stood down over the phone hacking scandal.
There has speculation that the Leveson Inquiry could release emails and text messages sent between Mr Cameron and the former News International chief executive. According to Daily Telegraph columnist Peter Oborne, Mrs Brooks has kept all the texts she received from the Prime Minister.
Mrs Brooks has twice been arrested by Scotland Yard detectives investigating allegations of phone hacking, corrupt payments to public officials, and an attempt to pervert the course of justice. She was bailed and has not been charged. She will not be questioned about anything that could prejudice the continuing police investigation into phone hacking or any potential future trials.
Mr Cameron set up the Leveson Inquiry last July in response to revelations that the now-defunct News of the World hacked murdered schoolgirl Milly Dowler's phone after she disappeared in 2002. The first part of the inquiry, sitting at the Royal Courts of Justice in London, is looking at the culture, practices and ethics of the Press in general and is due to produce a report by October.