Judith Collins is back in Cabinet. But let's not forget, her resignation was for an issue separate from those detailed in Dirty Politics, so she has never been "cleared" of the behaviour revealed in the book

It's disappointing – if informative – to see how the government got away with rewriting the story of why Judith Collins resigned from cabinet last year, preparing the way for her return this week.

Here's the official line: Collins had to resign as a minister last year because of suggestions in a leaked email that she was part of a campaign to undermine Serious Fraud Office head Adam Feeley. A subsequent inquiry by a retired High Court judge concluded that Collins had not been involved in improper behaviour. This cleared the way for her eventual return to Cabinet.

This is largely misleading but, through simple repetition, it is now an accepted truth. Let's look at how it was done. What actually happened is that Collins was on a "last warning" from the National Party leader John Key when my book Dirty Politics was published in August 2014. The book revealed Collins as petty and vindictive; and a close friend and confidante of the attack blogger Cameron Slater.

The book showed, for instance, that Collins gave Slater information about a public servant who they believed had leaked embarrassing information about the National Government. Although they were incorrect, the man was publicly accused and attacked repeatedly on Slater's Whale Oil blog leading to death threats against him and his family. The public was naturally disgusted when Collins' secret part in these attacks was revealed.

The book also showed her feeding a stream of other information to Slater to use on his blog, and quoted their unpleasant communications.

Discussing National Party internal politics, she wrote: "Personally, I would be out for total destruction.... But then I have learnt that to give is better than to receive." She called this the Double Rule, meaning that if someone attacked, you hit them back twice as hard. "If you can't be loved, then best to be feared," she said. None of it looked like a person who should be a minister.

Meanwhile John Key was also being criticised over other revelations in the book, most importantly the well-organised dirty tricks operation being run from his office that used the Whale Oil and Kiwiblog blogs to attack and smear his political opponents. There was considerable fear within National that this would affect their vote in the approaching election. When the Dirty Politics issues continued to be raised week after week, National decided it had to take action to close down the criticism. John Key did not want to admit the dirty tricks campaign run out of his office, so they decided to try to take the heat out of the issue by forcing Collins to resign.

But there was a complication. The National Party leadership did not want to admit that any of the book was correct. They could not say that the book had been the final straw in Collins' resignation without having to answer questions about Key's responsibility for activities in his office.

So they came up with a sleight of hand. Key's office itself released a further email about Collins' links to Slater – concerning Collins and the campaign against SFO head Adam Feeley – and said that Collins was being asked to resign based purely on that email. Nothing to do with the book. Then Key announced an inquiry into Collins' actions that excluded any consideration of the revelations in the book and instead only covered the allegation relating to the SFO head.

The inqiury eventually found that Collins had not been undermining Adam Feeley. The government line became that Collins had been "cleared" of wrongdoing over the issues in my book.

Now, any moderately attentive school student could have seen that investigating Collins for an issue that was not in the book (but none of the issues that were in the book) was tricky; and that "clearing" her over one issue that was not in the book did not in any way "clear" her for the issues that were.

But at each stage there were media and commentators that repeated the government's line without pointing out its obvious flaws. They all knew about Collins' role in helping to smear the public servant and in feeding Beehive information to Slater, but somehow this didn't get in the way of repeating the comfortable John Key version of the truth.

This smoothed the way for Collins' return to Cabinet. The manufactured explanation for why Collins had to resign went together with the sleight of hand "clearing" Collins for the one allegation that came from Key's office, not the book.

It seems incredible that such a weak plan could work. But it did work. None of the revelations about Collins in Dirty Politics have been disproved by the government. They were, after all, in the people's own words. Instead the government relied on distraction and forgetting.

By yesterday, when Collins' reappointment was announced, the manufactured story had, for many people, the status of fact. A piece from Fairfax, for instance, explained that:

"It had become increasingly difficult for Key to justify keeping Collins out of Cabinet after she was cleared of any wrongdoing in the Dirty Politics allegations that forced her resignation."

National will quite likely come to regret allowing Collins back into Cabinet. The rest of us should regret how easily they could spin the news to justify doing so.