Rupert Murdoch has arrived in Britain, and has taken to his iPad to launch a series of attacks on UK government policy. His tweets - sent on Saturday afternoon, have increased speculation that he will use his appearance before the Leveson inquiry into media ethics to attack British politicians.
The 81-year-old News Corporation chairman and chief executive will be asked about the phone-hacking scandal, his oversight of his UK newspapers, and his influence over British politicians.
His son James, 39, who is appearing before the landmark public inquiry on Tuesday, is set to be questioned further about when he learned of evidence suggesting hacking was rife at the News of the World.
Court 73 at the Royal Courts of Justice in central London will be packed for Rupert Murdoch's evidence sessions on Wednesday and Thursday.
Already he has issued a series of tweets critical of UK government policy - in a sign that he may exact his revenge on David Cameron for ordering the Leveson inquiry in the first place.
His first tweet on arriving in Britain saw an attack on George Osborne, who has decided to loan the Internantional Monetary Fund (IMF) £10bn to shore up the global financial system.
His second tweet saw him attacking the UK government' policy of creating new wind farms:
Murdoch's appearance before Leveson will be the billionaire's highest profile public outing since he gave evidence to the Commons Culture, Media and Sport Committee last July.
Mr Murdoch told MPs it was the "most humble day" of his life and apologised for the phone-hacking scandal, but the session was disrupted when a protester pelted him with a foam pie.
The setting is more formal this time: the media tycoon will swear an oath promising to tell "the truth, the whole truth and nothing but the truth" before undergoing scrutiny at the hands of the experienced counsel to the inquiry, Robert Jay QC.
The Murdochs are appearing separately, meaning that James Murdoch will not be able to interrupt to help his father answer questions as he did in front of the MPs.
The Leveson Inquiry has a wide-ranging remit to examine the culture, practices and ethics of the press, and make recommendations for the future regulation of British newspapers.
It has already taken evidence on unethical and possibly illegal behaviour by journalists, and on relations between police and newspapers.
Inquiry chairman Lord Justice Leveson is now turning to contacts between politicians and the national press.
The Murdochs will be asked about the phone-hacking scandal, which led to the closure of the 168-year-old News of the World last July after revelations that the paper listened to the voicemails of murdered schoolgirl Milly Dowler.
James Murdoch is expected to face more questions about what he knew as executive chairman of News Corp's UK newspapers division News International, a post he held until February.
Two News of the World executives claim they warned him in June 2008 that the practice of phone-hacking extended beyond royal editor Clive Goodman, who was jailed in January 2007.
News Corp still owns The Sun, The Times and the Sunday Times, and has a 39% stake in satellite broadcaster BSkyB.
The inquiry has heard that a young Times reporter hacked into a policeman's emails in 2009 to unmask him as the author of an anonymous blog.
Rupert Murdoch will be asked whether he exerted undue influence over British public life through his papers and his regular meetings with top politicians.
He told MPs he met David Cameron "within days" of the 2010 general election and was invited to Downing Street by Gordon Brown "many times". Tony Blair is godfather to one of his children.
A small number of seats in the Leveson Inquiry hearing room will be made available to the public on a first-come, first served basis during the Murdochs' appearances.
But security will be tight to prevent any repeat of the Culture, Media and Sport Committee protest.
Lord Justice Leveson will hear evidence tomorrow from John Ryley, the head of Sky News, who is likely to be asked about the broadcaster's decision that it was in the public interest for a journalist to hack into the emails of back-from-the-dead canoeist John Darwin.
Also appearing tomorrow are Aidan Barclay, chairman of Telegraph Media Group, which publishes the Daily Telegraph and Sunday Telegraph, and Evgeny Lebedev, chairman of the companies which own the Independent and London's Evening Standard.
The inquiry has already heard from Richard Desmond, owner of the Express and Daily Star titles, and is expected to take evidence from Daily Mail and Mail on Sunday owner Lord Rothermere in the coming weeks.