He is inordinately proud of his bright red cushions and insists on sitting with one for the photos, giggling with delight.
"I like this contrast," he says of the dark grey sofa and the bright red. It is the only sign of any attempt at interior decorating.
He only recently moved into the apartment, which he bought after his landlady kicked him out of his Viaduct pad so she could move in.
He couldn't afford to buy an apartment in the Viaduct. The view is not as good here, but he's quite stoked because, unlike at the Viaduct, his one-bedroom apartment here has a study, as well.
"Every time I had breakfast I had to move my computer, which was a bit of a bugger."
A NZ Institute of Economic Research trophy he won as Reserve Bank Governor in 1999 is beside the television. Robert Wright's The Moral Animal - about the evolution of human behaviour - is on the table.
His artworks are still in bubble wrap on the floor. One is a print of Salvador Dali's Last Supper.
He's barely had time for supper lately. But he did enjoy Mr Hide's last supper a month ago. That meeting, at which Mr Hide first opened the Pandora's box that led to his downfall, by discussing co-leadership with Dr Brash, was at Burger King. It seeded the idea in Dr Brash's head that while he might not want co-leadership, he did want the leadership. Burger King was Dr Brash's choice.
"I happen to like many kinds of junk food."
So now here Dr Brash is, in his tiny apartment with his red cushions.
He has a board meeting tomorrow and then a caucus meeting, at which he will officially become an Act New Zealand Party member and then Act Party leader. He doesn't know where the meeting is and is still handling his own media. It could be a recipe for disaster - even when he had multiple media handlers to steer him away from gaffes and bad photos, he struggled to handle his media.
Now he says he is looking forward to the campaign: "I enjoy campaigning."
His efforts in in 2005 are running afresh on television screens this week to accompany the story of his coup - Dr Brash struggling into a speedway midget car, Dr Brash walking that accursed plank, Dr Brash saying it was not helpful for his MP Bob Clarkson to be talking about his left testicle. He remains puzzled at the media focus on his foibles and things like "me expressing regret about my Tauranga candidate talking about my testicles".
Dr Brash remains the same gentlemanly and good-natured soul he was in 2005. His corned beef and peas days are behind him.
"I've graduated a bit."
He submits quite happily to an audit of his freezer to prove this, even turning on a light to assist with the job. There are frozen peas and frozen corn and some cuts of meat - a boneless lamb roast, a big slab of fillet steak. Then there are two Big Ben pies. He hauls these out to show them off.
"The great thing about Big Ben pies is you can cook them fast. Which at the moment is about all I have time for, if I eat at all."
He's been so busy with this coup business that he's only had two meals a day. Judging by the contents of his kitchen, this is sultana bran for breakfast and a Big Ben pie for supper.
Since his success on Thursday, he has been eating better. He had dinner on Thursday night with all the other Act MPs bar Mr Hide and then yesterday morning he had breakfast with most of them, too. They no doubt discussed the Act brand.
He thinks his brand is the same as Act's and Act's brand is the same as National's was in 2005, when he led National. Those brands are good brands like low spending and economic growth. Hide's brand is not good. And he is also critical of National's brand now, saying it has a set of policies that are "dangerous for New Zealand's future".
He believes a vast number of centre-right voters are upset with National, despite the polls.
He is sidetracked by a book in his bookshelf - Nassim Nicholas Talbe's Black Swan: The Impact of the Highly Improbable. He hauls it out and goes on and on about people who thought swans were only white because they had never seen a black swan. Once they did see a black swan, they realised it was always logical that there would be other-coloured swans.
He goes on to talk about other events nobody even conceived of until they happened and then it seemed perfectly logical that they should have happened.
"The internet! Mobile phones, iPods. And 9/11! In retrospect, if terrorists wanted to create mayhem, what a logical thing it is to do to hijack aeroplanes and fly them into buildings." I finally asked whether he's telling us all this because he thinks he's now the Black Swan of the Act Party. Such symbolism from such a prosaic man.
"Well, no," he says, bemused.
"It's just a great book." Other habits are yet to go the same way of the corned beef. One that lingers is the "uuhh" he used to punctuate the beginning of answers to questions he doesn't want to answer. It comes out when he is asked if he has ever voted Act. He won't say, but he did say he voted Labour when he was younger and wilder in the 1960s.
"I was definitely on the left of the political spectrum. As were many. Alan Gibbs, his then-wife Jenny and I were close friends in the 1960s and we were quite left-wing. Not hippies exactly, but we were quite left-wing." Another that lingers is his frugality.
His coup means he will resign his directorships of Transpower and the ANZ-National Bank, which he says are now his main sources of income.
Fortunately, the man once renowned for washing his socks in hotel bathrooms to save taxpayers' money hasn't changed. As we leave he realises he has left a light on. He dashes back inside, crying, "Save power every hour, as the slogan used to be."
