But still no word from Grant Robertson, Shearer's deputy, without whom it's hard to imagine such a letter getting the numbers. Wait, here he is: "Duncan, I have now confirmed with the whole caucus. There is no letter. This is just made up. Apology?"
Annette King chipped in: "It's a whopper!" Even David Cunliffe: "Coup rumours ridiculous." Oh, and Gower wouldn't be on Nightline after all.
But if Garner looked for a moment like an America's Cup yacht, racing no one but himself, he was undaunted, and grinded on. "Labour MPs denying letter of course," he sighed. "Textbook coup, 60 day warning, man ban, letter, denials, denials, gone."
The truth is probably somewhere in the middle. I don't for a second believe that Garner made up his Labour caucus source. But it wouldn't be the first time a politician briefing off-the-record had over-egged, or the first time a journalist added a little egg of their own.
And while it pays again to recall the Australian example, where the pool of MPs publicly backing Rudd was tiny until all of a sudden it wasn't, the paradox this week could be that the full-blooded, absolute nature of Garner's assertion did Shearer a favour: had it been the standard-issue "rumours swirling" sort of thing, it's unlikely there would have been such a swift lockstep response from MPs.
Just a few hours before Twitter lit up on Tuesday night, Garner conducted an interview on his excellent afternoon programme with veteran Australian journalist Kerry-Anne Walsh, author of a new book, The Stalking of Julia Gillard. Garner noted that the book was about "a bunch of blokey journalists" doing Rudd's bidding. And, he said, he was "a bit embarrassed when I saw this, but you talk about reporters becoming players, and not reporters".
Walsh repeatedly speaks of senior journalists in Australia having become "pawns" in Rudd's game, "channelling the Chinese whispers of his spruikers and giving credibility and substance to exaggerated claims about the pretender's level of support within the parliamentary party".
It worked for Rudd but it's an ugly way of doing politics. It's the way it's been done in Australia for years.
It's the way it was done for large parts of the last decade in Britain, too. Tony Blair's Svengali Peter Mandelson was routinely "dripping pure poison" about his chancellor, Gordon Brown, behind the scenes. Brown's henchmen were doing the same, feeding selected media with anti-Blair gossip.
It became the norm, unremarkable. And it was toxic, sinking public perceptions of politics and media all at the same time.
I like personality in political reporting. I'm a total sucker for the sport of it all, as evidenced by the callus on my Twitter-refreshing finger. But the British and Australian example is best avoided.
