When it was discovered that the conversation had been inadvertently recorded by a freelance cameraman, the microphone was confiscated by the PM's security staff and Key shrugged off any concerns by saying nothing of much consequence was discussed.
But as his political opponents demanded he release the tape of the conversation, so voters knew what to expect if they voted in Banks and a coalition was formed between National and Act, the PM turned feral. He likened the recording to News of the World tactics, called in the police and claimed he was preventing us all hurtling down a slippery slope.
Imagine, he said, if a high-profile couple was discussing their suicidal son or daughter and their conversation was taped and a Sunday newspaper reported those details and that child committed suicide ... Er, yes. Imagine. What an unusual analogy, and nothing at all to do with a couple of political animals milking a photo opportunity for all it was worth.
Key has given the storm in a tea cup another burst of life by calling in the police, who have warrants to seize documents from media organisations. But it was a bizarre comment from Key that really raised eyebrows: he wasn't wasting police resources, he claimed, because under National the crime rate had lowered by 7 per cent so police had a bit of spare time.
Dear me. The Prime Minister really hasn't coped terribly well when talking off the cuff.
In the other corner, though, are the media. And few people trust or respect us. We are ghouls preying on human misery. We are beat-up merchants, turning a minor incident into front-page news. We have no respect for privacy, we are unscrupulous and would sell our own grandmothers to sell a few papers. So when a member of the media proclaims the taping of a conversation was an innocent mistake, people see one half of a Tui billboard.
Ultimately, National's lead in the polls is such that this will be a minor bump in its campaign.
But Key hasn't handled this well and it's only the public's even lower opinion of journalists that has prevented more damage.