Any other 75-year-old who has successfully battled cancer and recently fathered a sixth child might have reason to ease up a little as he toasts his birthday with family and close friends. But it's a sure bet that Rupert Murdoch, whose impact and achievements are among the most far-reaching of his generation, was not talking about retirement as he blew out his candles yesterday in New York.
Tomorrow he arrives in London for a formal reception at the Newspaper Publishers Association to honour his contribution to the media industry. What everyone, guests and competitors alike, will be looking for is the same thing: clues that, just maybe, he is starting to slow down.
When he married again in 1999, friends cried: "Thank God for Wendi." The marriage appeared to rejuvenate him. He spent more time swimming and in the gym, and the couple were seen out on the party circuit.
But there have been rumours in media circles for some months now that maybe the Wendi effect is wearing off, or even that the high-burn Manhattan lifestyle with two daughters under five is tiring Murdoch out. The suggestion is that he is spending fewer hours in the office and travelling slightly less.
What he has not shown is any sign of losing his sharpness of mind or his frightening grasp of detail.
"He can take you on an intellectual tour of virtually every nation of the world," says Howard Rubenstein, his personal PR man for 30 years. "I had lunch with him and Henry Kissinger last year, and the conversation was back and forth, country by country, taking in politics, government and economics. It was one of the most interesting and extraordinary lunches. If you didn't know his age, you wouldn't think he was 60."
At 75, Murdoch has been indisputably the most influential figure in the British media over the past four decades, and a major influence on this country's politics, popular culture, sport and industrial relations. Even now, his far-reaching impact is difficult to assess properly. He has won more elections than Tony Blair, transformed the newspaper industry through taking on the print unions at Wapping, destabilised the monarchy through his newspapers' revelations, transformed football into a game awash with cash and changed the face of British broadcasting with Sky TV, which dominates the pay-TV industry, having almost eight million subscribers. His personal fortune is estimated at £4.53bn and his impact on how people today consume media is profound.
Yet judging by the most recent interview he gave, Murdoch does not feel these achievements have been wholly appreciated in Britain. He has long nursed a resentment at what he calls "the broadcasting establishment", which he believes sought to strangle Sky TV at birth. Ranged against him he has always envisaged a legion of shadowy "establishment forces" - the Eton and Oxford people who will never welcome him into their ranks, despite the fact that he went to Oxford himself. Frequently he even appears to play up his status as bogeyman, saying about broadcasters: "It is perfectly natural that people would be a bit paranoid about me. They all hate me because of Sky."
This sense of being an outsider - and not wanting to belong - has been useful to him in business, powering his aggression and enabling him to become, as he recently described himself, "a radical agent of change".
How ironic, then, that to younger eyes, he has become that establishment he reviles. Murdoch now risks eclipse by young upstarts who, like himself 50 years ago, have the ability to think outside the box and the vision to use new technologies in radically different ways.
Nowhere is this more evident than with the anarchic power of the internet. The News International empire got the net wrong in the Nineties - simply pasting its newspaper and TV content straight on to the web - but Murdoch has made fresh attempts to get it right. Recently News International paid $580m (£340m) for the online community Myspace.com, where young people blog, swap music and reach out to networks of friends. These community sites will be the way to sell media content in the future, Murdoch has decided, and he has proselytised to the industry ever since.
In an interview this year for the BBC he said: "I think we're on the eve, you know, of an era, of a golden age for media. These, all these wonderful inventions are nothing if you can't put something on them - they've got to have content. And that's what our business is, creating or reporting news and creating entertainment. And I think we've got to do more of it and take advantage of these great opportunities ahead of us. But the world, the internet, is just beginning."
From his origins as the owner of one sickly newspaper in Adelaide, Australia, in 1952, Murdoch has bet his empire time and again on the latest big deal or visionary technology. Whether it was the rescue of The Sun, the move into television and film in the US or the creation of satellite broadcasters in the UK and Asia, the gambles have all paid off.
Outside Britain, this ballsy record on so many continents has won him enormous respect. The media industry veteran Barry Diller, one of America's richest men, described him as "the only truly great international entrepreneur functioning in the media business".
Yet here Murdoch still feels his status has never been properly recognised. Of Wapping, which revolutionised the British newspaper industry but cast him as a hate figure, he said last year: "I'm certainly very, very proud of it. And it'll be part of my legacy. It was only 20 years ago, but people are already forgetting it."
They may be forgetting, but at the same time they are also forgetting to hate him. We all remember the playwright Dennis Potter calling his despised cancer "Rupert". But who would call their cancer "Rupert" now? Murdoch's old nickname, the Dirty Digger, is rarely heard. In America, by contrast, where he owns the tabloid New York Post and the controversial news channel Fox News, his status as bogeyman is gathering strength.
"He is brilliant, of course. But I would like one of his first birthday wishes to be to atone for Fox News and start thinking about doing some good in the world," says Michael Greenwald, the independent documentary maker whose Outfoxed chronicled right-wing bias on Fox News. "Fox News's slogan, 'fair and balanced', is an outright lie. It is pretending it is a news station, but it isn't. It is the state media of Bush Republicanism."
However, both in Britain and America, the political establishments have never underestimated him. His papers have performed political U-turns for the sake of their proprietor's business. Margaret Thatcher admired him for providing "the only unbiased TV news in the UK" and bent over backwards to ensure that monopoly regulations did not hinder the owner of almost half the country's newspapers also controlling a major television station. Who could forget when it was "The Sun wot won it" for John Major at the 1992 general election, and the rapidity with which Murdoch switched support in 1997 to Blair? He has since wielded an influence with the Prime Minister dwarfing that of any other citizen and is recently understood to have sought assurances from Blair that he will serve a good part of his third term.
Media friends he has found harder to retain. Those who have worked for him have a habit of parting acrimoniously. "I just can't be bothered to talk about him," said Andrew Neil, who was Murdoch's trusted editor of The Sunday Times and also launched Sky for him.
But William Shawcross, his biographer, remains a staunch admirer. "Murdoch is a genius," he says. "He saw the media was going to be one of the growth industries. He has now been making up for lost time with the internet. In Britain there has been this hysteria about him for 20 years. He liberated the British newspaper industry. I'm not surprised that he is carrying on working. He saw China and India coming long before anyone else."
Perhaps this year's low-key birthday celebrations owe something to the exhaustion of life in Manhattan. For a man who has spent years commuting between continents - and is said to give himself enemas on the company jet to avoid the bother of ordinary digestive complications - life with a young wife in the world's most frenetic city may just make him feel his age.
He caught sight of Wendi Deng, a former vice-president of his own Star TV, when touring the Hong Kong offices, and married her on a yacht in New York harbour just a few weeks after his divorce from Anna, his wife of 32 years, became final. Six foot tall and ambitious, Wendi immediately got her ageing husband into the News Corp gym, lifting weights and streamlining his diet to overcome the prostate cancer he had developed.
Last year it emerged that the couple had fallen prey to the problems of ordinary mortals when they couldn't sell their house. After Murdoch snapped up Manhattan's most expensive flat, a 20-room Fifth Avenue penthouse once inhabited by one of the Rockefeller dynasty, for which he paid a reported $44m, The New York Times was invited in. There we learnt that Murdoch enjoyed relaxing on the 2,700sq ft split-level deck with enclosed sunroom, found the need for 20 phones, and had entertained Russell Crowe, Ariel Sharon and Gordon Brown to barbecues on the roof.
But it is Wendi's ambitions for her offspring, daughters Grace and Chloe, that have thrown up the greatest complications in the Murdoch dynasty. For the question that grows heavier with each milestone birthday is: what happens after Rupert?
This year, the issue is more troublesome because his most favoured son, the tattooed, motorcyling Lachlan, flounced out of the company last July, ripping up Murdoch's succession plan. Murdoch Snr's public statement of "disappointment" isn't the half of it. Lachlan, the middle of the three children by Anna, had climbed highest in the family business after a Darwinist exercise run by his father. He was the number-three executive at News Corporation but was put out by Wendi's attempts to improve the inheritance of his infant half-sisters.
Desperate to ensure the running of the business stays in the family, Murdoch is now in a race against time to groom his younger son, 32-year-old Harvard drop-out James, who currently runs BSkyB but has yet to really prove himself.
Mathew Horsman, media consultant and author of Sky High: The Rise and Rise of BSkyB, predicts that Murdoch will find it hard to get his own way in the long run. "It is difficult in a public company this size to ensure a family succession. It is controlled by Murdoch, yes, but not majority-owned by him."
Last year even Murdoch's mother, the 96-year-old Dame Elisabeth, suggested someone outside the clan might succeed him at the helm of News Corporation. "You can't tell how long Rupert's going to live and ... he'll find it extremely hard to hand over to anybody," she remarked, speculating that "somebody outside the family" might run News Corp when Rupert falls under the fabled number 11 bus.
"If in the future it looked as though somebody else was better for that position, he would be very practical and accept it, and be grateful that there was somebody capable," she suggested.
Murdoch himself doesn't really want to talk about it. He dislikes any reminders that he is getting old and is in denial about his age. He has no plans to slow down. Kelvin MacKenzie, the former editor of The Sun, believes Murdoch will never satisfy all his ambitions. "He's an amazing guy," MacKenzie says, "his energy and his interests allied to a big dollop of common sense. Rupert will never have completed his task by the time he leaves this earth. He's a huge restless spirit."
Not so long ago Murdoch revised his prediction of giving up at 100 by announcing that he was postponing retirement "for ever". Whatever he says in London tomorrow, it is on that detail that media commentators around the world will be most keenly awaiting an update.
Additional reporting: Stephen Foley in New York and Sophie Goodchild in London