The focus now is on contradictory statements Rupe made about his lunches with Margaret Thatcher.
Robert Jay QC, counsel for the inquiry, highlighted the issues on Thursday as he opened its third module - dealing with relations between media figures and politicians.
"The acquisition of the Times and its associated titles must have been one of the most important in his commercial life.
"This was a time of heightened emotion. Could an intimate lunch at Chequers really have been forgotten?
And then counsel employed a rhetorical device that I find quite brilliant -
"Human recollection is notoriously patchy and unreliable, we all know that. The fact that I, for example, would be 100 per cent certain of being able to remember an event such as this occurring 30 plus years ago is not going to assist you in coming to a conclusion either way."
Jay said if the inquiry accepted Mr Murdoch's evidence the "point goes not further".
"But if you do not the consequences are capable of being wide ranging," he went on.
"Not merely would the selective amnesia appear to be convenient but inferences might be drawn as to Mr Murdoch's true motives and intentions seeking out the prime minister's ear in January 1981.
"Furthermore this case is capable of bearing on Mr Murdoch's integrity."
If, in fact, the inquiry decides that Rupe did indulge in a bit of highly-selective memory, a very delicate term for lying, then straight out the window go his other self-serving denials about not knowing anything about the voice-mail tapping or corruption of police officers and on and on and on - the sort of stuff most of us have long assumed he was lying through his teeth about.