"I had no idea what was right and what wasn't," he recalls. "I think my first question was, 'why are you here?' because I didn't really know what he'd done. We just had to get him on the record and see what happened next."
On TV One's Seven Sharp, Metro magazine editor Simon Wilson perched alongside Ali Mau, as Jesse Mulligan and Tamati Coffey looked on. The interview led off with sniggers about Wilson's comment in a feature article that month: "If politics was sex, Len Brown would be on top."
If one evening were to encapsulate the shift in television current affairs this year, that October night might be it. TVNZ's Seven Sharp confirmed, once and for all, that it had surrendered the current affairs battle.
"That night really does sum it up, the trivialisation of what's happening in news," says media commentator Janet Wilson, a former award-winning current affairs journalist.
"But it's not just in Seven Sharp, it's happening everywhere."
There's no doubt in Campbell's mind that, not all that long ago, a politician in Brown's situation would have headed for TV One.
That has changed. "We've become the programme of record."
Wilson and other commentators say this has been Campbell's year. In the 7pm battle, Campbell Live is on top when it comes to critical acclaim and official acknowledgement. It comes on the back of agenda-setting stories such as food in schools, Novopay, John Banks' campaign donations and the troubles at Solid Energy.
Also this year, TV3 launched 3rd Degree, hosted by erstwhile rivals Duncan Garner and Guyon Espiner, with colourful investigations into a Taranaki cabbie at war with an entire city, the Teina Pora miscarriage of justice case, and the black marks on David Bain's father's fingers.
But there's one area in which TV One is still dominant: the ratings.
There are two schools of thought. One says TVNZ's continued stranglehold on prime-time TV ratings is a shortlived lag, that TV3 has grabbed the news and current affairs crown from TVNZ and, with it, its credibility. Ratings are sure to follow.
The other school says TVNZ is one step ahead with i, making an initially unpopular but ultimately far-sighted decision to give viewers what they want - interaction, entertainment, engagement.
Seven o'clock is one of the most competitive - and commercially important - time-slots on television. Paul Holmes held the mantle from 1989 until November 2004 when he defected to Prime TV. That same month, TV3 announced its assault on the 7pm ratings with the launch of Campbell Live.
For four glorious months (at least for current affairs junkies) there was a three-way current affairs battle at 7pm: the fading prince Paul Holmes, the moustached heir-apparent Mark Sainsbury, and the brash new pretender John Campbell.
Of course, the three were fighting over the scraps of power. i was firmly ensconced as ratings king, seemingly unassailable. That has never changed, as first Holmes, then Sainsbury, fell by the wayside.
When TVNZ announced Sainsbury's departure last year, it said it was planning "a new daily current affairs show with a distinctively different format". Just how different took a lot of people by surprise.
Instead of one host, there were three - one best known as a comedian. The interaction with the audience was jarring. Reviewers called it "fluffy", "clumsy" and "barely living up to low expectations".
It debuted at the beginning of February with an average audience of 496,950, well up on Campbell Live's 242,800 (viewers aged 5-plus), but within two weeks had lost most of those viewers, falling to 242,300.
John Campbell stepped into the gap. Some might say he was lucky, but he is not superstitious. He would probably say you make your own luck.
On February 12, Campbell Live checked out grocery prices in London and New Zealand, interviewed Winston Peters about NZ First MP Richard Prosser's "Wogistan" outburst, talked to expat Kiwis about their struggles on the Gold Coast, and announced the return of Marmite.
Seven Sharp asked Kiwis in the street about the Pope's resignation ("they weren't too fazed"), and threw reporter Matt Chisholm overboard without a lifejacket to see how long he lasted. On Wogistan, they had to settle for an interview with Investigate magazine editor Ian Wishart. "Ian, you're the closest thing we could get to Richard Prosser," Ali Mau bemoaned.
That night, for the first time in TV3's 24-year history, the privately-owned network beat the state broadcaster in the 7pm ratings battle.
Since then, Seven Sharp viewer numbers have been down 16 per cent on Close Up's average last year.
Presenter Greg Boyed quit in September, and the show has been trialling replacements ahead of an announcement soon.
Pundits put former weatherman Tamati Coffey a nose ahead of children's TV graduate Stacey Morrison.
Yet, despite its rotating cast of presenters, Seven Sharp is clawing its way back. It is now pulling in an average 384,276 per episode - nearly a third higher than Campbell Live's 308,638.
And as Seven Sharp prepares to wrap up its first year next week, those ratings matter more than all the celebrity banter and snappy repartee in China.
The battle for primetime ratings begins not with the triumphal power chords opening the six o'clock news bulletins, but half an hour earlier with that familiar, gently-lilting theme tune we remember so well. "You know we belong together, you and I forever and ever ... "
Yes, while the media critics debate the merits of Seven Sharp, TVNZ's undisputed coup was in August, when it stole the rights to Australian soap Home and Away from under an unsuspecting TV3's nose.
For more than a quarter of a century, that show has chronicled the lives, loves, happiness and heart-breaks of the residents of Summer Bay, a small coastal town in New South Wales.
Brax has been sentenced to more than 10 years in prison for killing Johnny; he tells girlfriend Ricky she must leave him to make a life of her own on the outside. But Ricky discovers she is pregnant. Should she tell Brax he's going to be a daddy?
Since 2002, Home and Away had screened on TV3 at 5.30pm and then delivered many of its loyal fans to 3News at 6pm. Once the channel control was stuck on 3, it often stayed there all evening.
When TV3 lost the soap, it also lost about 20 per cent of its news audience. Five weeks before the shift, TV3 news' average audience was 329,356 per episode. Five weeks after, it had plummeted to 266,686. By the beginning of this month, it had dropped to a low of 224,110.
One News pulls in an average 653,637 viewers a night, compared to 3 News' 305,093. Indeed, TV One out-rates TV3 in every news and current affairs slot.
TVNZ's head of news and current affairs, John Gillespie, says they're winning any battle that's being fought. Seven Sharp was a deliberate decision to move towards a format that viewers wanted.
"It has current affairs shot through it but it's probably more a programme that has a decent conversation with New Zealanders.
"I see us changing the space current affairs inhabits, not moving away from it. People judge with their remotes and Seven Sharp is definitely something they want to see."
Broadcasters worry about ratings because they equal advertising dollars. Advertising consultant Martin Gillman says the loss of Home and Away was a big hit to TV3's bottom line. On the basis of the additional audience TVNZ was claiming from 5.30pm and through the evening, the broadcaster could expect to make an an extra $10 million to $12m a year.
He says revenue is typically split according to audience share, though TV One's slightly older audience is seen as less valuable to advertisers.
Advertisers prefer the 25-to-54 age demographic, he says, in which Seven Sharp and Campbell Live have about 6 per cent each.
Gillman estimates that each show pulls in about $22,000 in advertising per episode and $4500 in sponsorship, grossing just over $6m a year each. He estimates Seven Sharp's Rabobank partnership to be worth $1m to $1.2m a year.
Across the networks, TV advertising revenue is worth about $540m a year, of which Sky and Prime claim $70m. TVNZ reported ad revenues of $311m, leaving about $159m for Mediaworks, "roughly in proportion to commercial audience share".
TV3 has been claiming double-figure increases in revenue across the past two quarters. Whether it can maintain that growth without Home and Away remains to be seen.
The problem for TVNZ is that the integrity of the news and current affairs offerings affects the credibility of the network.
TV3's 3rd Degree has been critically heralded as one of the year's success stories, even though it doesn't rate particularly well.
The Vote, also featuring Garner and Espiner, had its final outing this week. It was a ratings flop, so The Vote and its host Linda Clark won't be back next year.
"Not everything you try comes back for a second term or continues on," TV3's head of news and current affairs, Mark Jennings says.
"But if you don't try anything, you don't develop as a news network."
This has been been a watershed year for TV3, he says. "It was a huge move for TVNZ to move out of daily current affairs. We were used to fighting tooth and nail with Close Up on a daily basis but that's changed."
And that has made it easier in some ways. "Take the Len Brown interview - there was not really anywhere else for him to go. He was never going to go on Seven Sharp."
TVNZ would bridle at the suggestion that it has "moved out of current affairs". Indeed, commentator Brian Edwards says TV One's Sunday is a current affairs standout.
"I've recently seen them devote an entire programme to an individual topic, which works very well," he says. "They've had some very good, very interesting stories."
Sunday rates an average 600,000 viewers, more than TV3's Campbell Live, The Nation and 3rd Degree combined.
Presenter Miriama Kamo, who also fronts Marae Investigates, says people want to see more of New Zealand on screen. "What people respond to is our local stories. They want to tune in and see themselves."
So has TVNZ changed the game, or lost it? While Campbell Live was doorstepping John Palino at the end of October, asking how much he had to do with the release of details of Len Brown's affair, Seven Sharp's Tamati Coffey was gushing over Dolly Parton.
Janet Wilson says the shift towards lighter current affairs has not worked and Seven Sharp needs a complete overhaul.
"Seven Sharp is patently a failure on many levels.
"A lot of people love the fact they're getting information in bite-sized chunks.
"But, at the end of the day, it's like eating candy floss for months on end - you end up feeling slightly sick.
"Too much junk food is not good for you and Seven Sharp has proved that in current affairs terms."
The critics said much the same about the Holmes show, though, when its brash young host provoked America's Cup yachtie Dennis Conner into storming out in the first episode, way back in 1989.
Nearly a quarter-century on, the show is fondly remembered for some of the best and most popular current affairs journalism in our history.
At TV3, Campbell says he doesn't give much thought to his competitors. Worrying about what other people are up to never got anyone anywhere, he reckons.
"It's like being in a sports team. If you're an All Black centre, there's no use worrying about the other centres in New Zealand. All you can do is play your best game."
It's Friday, the end of the week. He and his production team have been responding to emails from viewers (pleas for help still come in daily from people left out of home and out of pocket in Christchurch) and trying to persuade the day's newsmakers to appear.
The question is whether they're going to front - there's no longer any question about where they're going to front.
Shortly before 7pm, Campbell heads to the studio, pulling on his tie at the last minute - the signal the show is ready to go.
It begins with a tribute to Nelson Mandela, which a team of reporters and editors have spent the afternoon pulling together.
Then, a story about the mutiny by taxi drivers at Auckland Airport.
The story came in much the same way that lots of Campbell Live stories do - Campbell was doing a piece at the airport earlier in the year when the cabbies approached him.
Is Campbell nervous as he goes back into the breach?
No, he replies. It takes a bigger battle than this to make his heart race.
Just don't wish him luck - he doesn't like that. "I'm very averse to superstition."
