Eric Abetz's relationship with Peta Credlin never recovered after an incident while the Liberals were in opposition. A stunned Abetz, the most senior conservative in the party, later related the story to colleagues. During a meeting in his office with Abbott and Credlin, the leader's chief of staff was berating him. Abetz, unimpressed, waited till she'd finished then rebuked her: "May I remind you that you are a member of staff?" Credlin's response was volcanic. She shouted angrily at him and left the room, slamming the door behind her.

Abetz turned to Abbott and said that if she had been on his staff that would have been occasion for her to receive a first, second and third warning. "Peta will apologise in her own way," Abbott assured him. If she did, it was so subtle that Abetz couldn't detect it. Despite this incident, he was one of Abbott's staunchest supporters throughout his term as leader.

In another incident, Credlin was angered and distressed by a column in The Australian by Niki Savva that appeared on October 30 last year. The particular sore point? Savva reported that Credlin had organised a dinner launch for a group to mentor Liberal women staff in Parliament House. The guest speaker at the dinner was Abbott.

Savva thought it odd that Credlin had not invited the only woman in the cabinet and the deputy leader of the party, Julie Bishop, to the dinner. Relations between the two women had been increasingly difficult. Credlin was unhappy that the Savva column could contribute to the impression that she was trying to freeze Bishop out.

Credlin sent a text message to the newspaper's editor in chief, Chris Mitchell. He tells Fairfax Media: "For several months she'd been complaining about Niki and the text said 'I've had enough, you have to sack her'."

Mitchell replied that in 24 years as an editor no political staffer had ever made such a request and that he was shocked that she would ask.

"Then Abbott got on the blower," says Mitchell. "He rang me about 10 minutes after my response to Credlin.

"He asked me why I'd object to Peta's request to sack Niki when I had sacked Glenn Milne [an earlier columnist at The Australian] at Julia Gillard's request. I explained to him that that wasn't what had happened."

Abbott denies asking for Savva's sacking, but Mitchell says that was exactly the interpretation he'd put on the prime minister's call.

Credlin also phoned the political editor of The Australian, Paul Kelly, in an effort to enlist him in getting redress, but without result.

Abbott looked for another way. He phoned his deputy and asked her to come to his office. The Foreign Affairs Minister found Abbott with Credlin in a tearful rage.

As an amazed Bishop later told colleagues, Credlin yelled: "I'm a f…ing volunteer. I'm not an elected MP, I don't have a voice, I can't defend myself in public. I shouldn't have to put up with this shit."

By the end of the two Abbott years, this would become a familiar Credlin mantra to government insiders.

In this account, the prime minister made efforts to console her, and asked Bishop if she could do something to "fix" the situation. She said she didn't know what to do. Credlin left the room in a huff. Abbott asked Bishop to have lunch with her.

Bishop agreed, in this account, but the lunch never materialised. Abbott, however, has since denied that any such incident occurred, describing it as a "fantasy".

Credlin's temper was legend in the Coalition's ranks. "The whole government went around on tiptoe, frightened of her tantrums," a minister said.

Some ministers, however, worked well with Credlin over the years, including Christopher Pyne, George Brandis, Joe Hockey and Andrew Robb. Others, like Scott Morrison and Greg Hunt, made sure to establish firm limits to her influence over them and managed to co-exist.

If Credlin was frustrating for ministers, she was mystifying to the wider public. The ceaseless chatter inside the government about the Credlin-led operation – the internal shorthand for it was "command and control" – filtered into press gallery reporting. Credlin was always visible at Abbott's side in public. She developed a media profile.

Barnaby Joyce says that "Peta had great strengths and she was across the issues. But when you have cartoons in the paper about a staff member it means they're not doing their job.

"There are no cartoons about Tony Nutt [former John Howard political fixer and now federal Liberal director] and very few about Arthur Sinodinos [Howard's chief of staff for a decade and now a senator].

"The Australian people expect their political figures are people they elected," Joyce continues. "'Who's that?'" – he mimics pointing a finger at Credlin – 'You are the servant of my servant, not some ordained higher power.'"

Of course, if the Abbott government had been successful in the polls, the Abbott-Credlin duumvirate might today be hailed as a brilliant model.

But it was not. Members of that government commonly blame the partnership as the central flaw in the government's conduct, its decisions and its inability to recover.

Abbott once publicly complimented Credlin in the House for being "the fiercest political warrior I've ever worked with".

Professor James Walter, a political psychologist at Monash University who has made long study of the workings of prime ministerial offices, says that a political warrior is "the wrong sort of person" to run a prime minister's office.

The position requires someone who understands how government works, knows the public service, and can co-ordinate all parts of the government while protecting the prime minister.

"I find Tony Abbott's misjudgment astonishing; that sort of choice for a chief of staff and then his unwillingness to reconsider when things were clearly going pretty badly."

Why was he prepared to lose power rather than lose Credlin?

It was "a deep co-dependency", says a senior public servant who saw a great deal of Abbott and Credlin together. A common way of explaining their closeness was to put it down to them having an affair.

Some Liberals and even people from outside the party confronted Abbott before the February spill over the affair he was supposed to have been having with Credlin, the least original rumour in Australian politics. They were worried less about the reality than the perception. Some feared that it could cost him the prime ministership, and told him so.

He dismissed it as he always did, as "just bullshit". Abbott consistently refused to dignify what he described privately as "smut" by taking any steps to dispel the gossip. There was always a stream of innuendo, never any evidence.

"Because I'm a male and she's a female, why does it have to be improper?" he said to a confidant. "I think the talk says more about the colleagues than it says about Credlin and me." He described Credlin and her husband, Brian Loughnane, as both very good friends of his.

Another said: "He would sometimes become visibly agitated when he was separated from her, if they had to travel in separate cars or even if she didn't emerge from the lift pronto when he was expecting her." It was "the most extreme of these sorts of co-dependency relationships between a prime minister and a chief of staff" according to Professor Walter.

Credlin herself says that she was the victim of sexism. She would explain repeatedly during her time in office that "because I am female, and I'm not 20 stone, and I'm in a position of power, the media put me on the front page and on the TV in a way they never did with Arthur Sinodinos".

Quite so. But it's also true that Sinodinos did not conduct himself in a domineering manner when he occupied the same position for Howard. On the contrary, he was always deferential and collegiate, as many Liberals who worked in that government attest. No chief of staff before Credlin had ever behaved as an equal in the cabinet, giving her views on issues under discussion, even interrupting the prime minister to make a point.

Credlin's diagnosis of the problem, however, helps explain the attempt that she and Abbott made to rectify it after the February "near-death experience".

Credlin disappeared from public view. She also stopped attending cabinet meetings. Abbott started holding monthly meetings of his whole ministry, not just his cabinet, and hosted many small dinners for colleagues.

"But it was still tightly controlled and the meetings were box-ticking exercises," said a minister, reflecting a widely held verdict. Credlin continued to join the daily meetings of the government's leadership group. "There was no real change," the minister concluded.

She also said publicly, after Abbott had been ejected: "If I was a guy I wouldn't be bossy, I would be strong. If I was a guy I wouldn't be a micro-manager, I would be across the detail," she said.

"If I wasn't strong, determined, controlling – and got them into government from opposition, I might add – I would be weak and not up to it and would have to go and be replaced." This explanation has some outward plausibility, but it affronts many of the Liberal MPs and staff who worked with her.

Some of the most aggrieved about Credlin's behaviour were some of the most capable women in the Abbott government. Not only Julie Bishop but Kelly O'Dwyer, Concetta Fierravanti-Wells and Michaelia Cash, for instance.

The veteran political journalist Michelle Grattan has said that it was not Credlin's gender but her behaviour that was the issue. She wrote on The Conversation website: "Abbott used to say if Peta were Peter, she would be treated differently. More likely is that if Peter had behaved as Peta did, he would have received a kicking too."

And when Bishop advocated putting more women in the Abbott cabinet at the outset, the most strident opposition came from Credlin. Bishop nominated Marise Payne and Sussan Ley, both now in the cabinet. Credlin replied that there were no women good enough, during a leadership dinner at Canberra's Ottoman restaurant soon after winning the 2013 election.

When one of the two women in Abbott's shadow cabinet, Sophie Mirabella, lost her seat in that election, Abbott preferred to shrink the Cabinet from 20 to 19 rather than include an extra woman.

Women, said the Liberal MP Sharman Stone soon after Abbott lost power, "were actually put back a step for Tony's ministerial line-up", contrasting the Abbott cabinet with John Howard's.

"Peta's had a Damascene experience somewhere and she now sees that, yep, women should be there."

A female junior minister sums up the view from inside the government: "There was a disconnect between Peta's stated support of the sisterhood and the sisterhood."

Credlin's ultimate defence is not her own argumentation. All her power was borrowed, given by Abbott. She was what he wanted, allowed and encouraged her to be.

The former prime minister himself, weeks after losing power, gives his full endorsement: "Credlin is a tough operator," Abbott tells Fairfax Media.

"She has opinions and she tells you, sometimes vigorously. That's what a PM's chief of staff needs to do.

"It suited people who had a problem with me to say it was her. Ninety-nine per cent of it was distortion or fiction. [Where complaints were well-based] it was blamed on Credlin, but the decisions were mine."

Some days after the February spill, Fierravanti-Wells, a conservative ally of Abbott's, is reputed to have spoken to Credlin about the downfall of his government and prophesied: "One day Tony will be sitting on a park bench in Manly feeding the pigeons and he will blame you."

Not so, not yet at least. She acted in his name, and he is taking full responsibility for all of it.