In his book, Sir Bernard Ingham called her the "shouter". John Major once asked uneasily, "Who is that woman who makes me feel like a criminal every time I enter Downing Street?" She once wrong-footed Neil Kinnock with an adroit doorstep after an angry NEC meeting. "Are you happy?" she bellowed at Kenneth Baker, eliciting tell-tale anger as he emerged from Number 10 after being demoted.
Johnson was the BBC's political news editor, conducting the daily news operation out of Westminster, feeding the many bulletins' limitless appetite for soundbites - 20 seconds and not a nano-second more. It's a tough skill in a tough scrum, and she was the best.
That is why the Labour Party hired her a year ago. And why it has come as a shock to those of us who worked with her in the newsroom to hear of her acrimonious departure from Walworth Road on Monday. I tried to find out what went wrong.
As Labour's Campaigns Director, Johnson was responsible for media strategy, for campaigns in the 80 target seats, and for what are called "rebuttals". "But I was always better at attack than defence," she says, recalling sallies such as the Chicken Run, teasing Tory MPs fleeing losing seats to find better ones. "You can't put a good spin on a bad story," she has always said, but then she has been shocked to find some journalists surprisingly easy to spin: "I'm against the lobby system, which just spoon-feeds journalists. Some journalists are not at all rigorous. Some are lazy, some are too keen to keep in close to power."
So why has she been ousted from her job in the run-up to the election, which she admits she will miss painfully? The inside word was that she was part of an attempt to stop all power being sucked upwards into the leader's hands, while she herself would only admit to her natural journalistic instincts jarring with political imperatives. The truth? Even for this, her one and only interview, her lips are zipped , even if her eyes are expressive.
Trouble first surfaced publicly on the October night Tony Blair was making his leader's speech to the party conference - which fell on the same day as the OJ Simpson verdict. Without consulting Johnson, Blair's press secretary, Alastair Campbell, sent a fax to the BBC demanding that the Labour leader should come ahead of OJ in the news running order. The BBC director-general's brisk and rude response called the fax "crass".
"I was shocked when I was told about it," she says - probably because she knew full well that the speech would lead the bulletins anyway. That incident defined the tension between herself and the leader's office that was eventually to become unendurable.
Yesterday Labour was saying nothing openly about her departure. But off the record, a picture emerges in which Johnson became a player in both a key personal rivalry and a prime clash between old and new Labour styles of politics.
She was hired by Gordon Brown, Shadow Chancellor and head of party campaign strategy. Her appointment was approved by Tony Blair, though she made no secret of her personal politics: "I had wanted Gordon Brown to stand for the leadership. I believe he really wants a fairer society - and means it. When he didn't stand, I voted for Margaret Beckett."
Like other parties, Labour's press operation has an awkward division between the role played by press officers working out of party headquarters and the team in the leader's own office.
What made the split so deadly for Johnson was that this division emphasised a growing chasm between Tony Blair's people and Gordon Brown's people. You could try to dress up the animosity in the respectable clothes of policy difference and matters of substance - but the players would still look pretty naked. The fact is, most of politics is far more about personal rivalry, jealousy and suspicion than usually gets reported.
For there is but a cigarette paper between the politics of Brown and Blair. The story of their falling out is a fine human drama - a Cain and Abel, a Romulus and Remus. One man nobly stands down for the good of his friend and his party. But he remains embittered, his friend's gratitude never lasts long enough, and living in the shadow of such a bright sun is more painful than anticipated. Political leadership is absolute and leaves even the closest colleagues far behind in the second rank.
The charge against Johnson is that she set about promoting Brown in particular, to offset the overwhelming publicity given to the leader. She rejects that, and says she promoted the whole team. New Labour, however, is presidential in style, and as she has discovered painfully, that it is the only game in town, the growing face of modern politics everywhere. One of her predecessors, John Underwood, fell under the same steam train.
Will they replace her? "Oh, I don't think they will!" she says with a quick, sharp laugh.
Johnson's fall has exposed the venom between the Blair and Brown camps. One Blairite said: "No, no, I couldn't possibly talk about it. Absolutely not. We are injuncted not to say a word about what really happened." But it took about a minute and a half and very little prompting before the dam burst and a bilious wave engulfed Johnson's reputation. It would be too libellous to print, but suffice it to say that what followed was a string of vitriolic insults.
There followed a tirade along these lines : "She was working for him [Brown] and him alone. You should ask X [a Brownite], who is a very intimate friend of hers, and a poisonous individual. She was part of a complete organisation, working just for him. "
I bounce these epithets off her, hoping to elicit a response. Her eyes widen, she looks hurt, but her lips stay zipped - almost. "You won't get me to say anything. You can think what you like about the people who say such things. I do reject any accusation about my competence. Perhaps it speaks volumes that this all comes from one side?"
Indeed, plenty on the other side are full of indignant praise for her, and anger at her untimely removal.
For outsiders, the wonderment of Westminster is that politics expends so much passion about so little. Commentators delight in the Shakespearean tragedies played out in sound and fury, though they signify nothing more than the fascinatingly fissiparous tendencies of all human organisations, from street committees to the floor of the House.
This, it has to be said, is the most minimal interview I have ever conducted, since Johnson was determined to say as little as possible in the hour and half we spent together. "Why did I ever agree to this interview?" she asks at the end, suddenly panicked that she might have said something that mattered after all. "Because it's good to talk," I said, with irony. But the only talking that goes on is behind the scenes, and it is fierce and acrid in the safety of absolute deniability.Reuse content