The evidence is there online: Rupert Murdoch's faltering and bemused appearance at Westminster on Tuesday was not merely an example of his unusual conversational style, nor a deliberate act intended to win sympathy from a global audience.
The lost figure who struggled to answer, and sometimes to hear, the words of his questioners this week, shocked some investors in his company, News Corp.
A comparison of interviews available online demonstrates how time has caught up with News Corp's founder and undermines suggestions by Murdoch loyalists yesterday that hesitation before answers is a long-standing Rupert trait.
"Those long pauses are a Murdoch characteristic which goes back a long time," claimed Trevor Kavanagh, one of the most senior figures on The Sun. "Those who portray him as a doddery old man are very far from the truth. He's an old man, there is no disguising that, but... he has a razor-sharp mind."
But when the media mogul was interviewed in 2003 by Jeff Randall, then the BBC Business Editor, he displayed a very different fluency.
Asked by Randall to compare the British economy to those in Europe and America, Murdoch offered lucid economic analysis. "I believe that if America can keep a growth rate of 4 or 5 per cent a year for four or five years, it's going to leave Europe even further behind. But that, again, comes to how is Brussels going to behave? What's going to happen with this new Constitution? What central powers will come in? How it will affect this economy. I'm one of those who think there are great dangers ahead."
Murdoch's biographer, Michael Wolff, was dismissive of ideas that the halting responses were an attempt to draw sympathy by a man determined to show his humility.
"This is the way that Rupert is. Within News Corp they try to tell you 'Oh, he's just thinking. Oh, he's just concentrating.' I have watched this up close and he literally departs this space for the moment. He can't focus on a conversation and he can't hear," he said, adding that there was an "Emperor's New Clothes" situation at News Corp.
"Everybody walks around that building in New York and that company worldwide and pretends that everything is fine. There is... this incredible denial about what's in front of your face: that Rupert Murdoch for several years now has been losing cognitive function."
Even those close to Murdoch for many years acknowledge the change. "Some people thought he was hamming up and deliberately appearing old and frail to win the sympathy vote. Others thought it was part of his general demeanour. I disagree," said one admirer.
"I thought he looked old and confused and slow. There are moments of intense lucidity but then he drifts away. I just think it's simply the ageing process. Had I been a professional investor I would not have been impressed with that performance."Reuse content