Sir Roger Douglas says he'll meet me outside Foodtown, at the Manukau City shopping centre. This is because his wife has a bug and so is not keen on having people over to the house. But still, what a perfectly wonderful idea: going to interview the former finance minister, the man whose name still causes a visceral response in some, near adulation in others, in a mall, that temple of sorts to the free market.

On the phone as we were arranging this date a disconcerting thing happens. As soon as you hear that voice you are transported back to the tumultuous days of the mid-'80s and the Lange government. He says, "This is not a witch hunt on Act is it?" And "I know it's [this page] where you give us all hell." And, without any encouragement whatsoever, "The bloody country's going down the tubes."

I say the shopping centre's good and that I'm sure I'll recognise him because who alive during those times wouldn't? The face, even without the moustache which was the trademark of privatisation for so long, is unmistakable. But goodness, how could I have forgotten what a little fella he is?

Despite this, I do spot him easily. He's the one sitting on a bench, the silver-haired joker in the khaki pants and checked shirt with the Lotto tickets sticking out of his pocket. The former finance minister, Sir Roger buys Lotto! "No one ever got rich being a politician," he says. "Anyway, even if you were rich, you'd still take a Lotto ticket. I'm a bit of a gambler, you see."

They should use him on the ads but I can't make up my mind whether they should use him on the ads exhorting us to buy Lotto, or the public service ones telling us not to gamble. It would give him something to do and might keep him out of what hair Rodney Hide has left - for a bit.

He wouldn't do it of course: either go on an ad or get out of Rodney's hair. The first thing he wouldn't do because he doesn't approve of politicians gallivanting about making horse's bums of themselves. That's my term but it's what he means when he snorts when I ask whether he thinks it would be a good idea for Rodney to appear on Dancing with the Stars. He then splutters "Dancing with the Stars!" in the exact tone he uses to say "this Labour Government". Which is to say that he doesn't need to add "my arse" at the end, it's all there in the sneer.

The first thing he did when we meet is to pretend he's "about 80" and make a great play of being decrepit. Then he strides off, looking fitter then a fiddle, in search of coffee. After the interview he asks how old I think he is. "80? 70?" He's 68 and once we sit down he stops pretending to be ancient and says with keen interest: "What's this about then?"

What it's about is how he's popped up again, at the Act conference, like the spectre at the feast, being mean about Rodney. But first I stupidly asked him why he'd still been asleep at 9 am when I called on Tuesday: "Had he been out with the Blairs?"

"I don't think I was invited for some unknown reason. I don't understand why Helen doesn't invite me. Maybe it's because I've said this is the worst Government we've had in 50 years." By my calculations, I tell him, it has taken him 18 seconds to get in a dig. He says he got plenty more in earlier in the day when he did an interview with radio. "So I'm partially warmed up."

You suspect that he needs little invitation to get warmed up. He still talks about himself as though he's a sitting politician. He says apropos of muck-raking politics: "That's why I get wild when we talk about scandals and things like that which are irrelevant. We ought to be talking about Mrs Faleauto and how her five kids can get the same quality of education as anyone else," and "You see, the point is that I still actually care about that constituency which I represent."

But he's not an MP and my point is that he's not exactly being helpful to Act, is he, turning up and giving a speech criticising Rodney Hide's leadership style. He doesn't need me to conduct a witch hunt, I tell him, he's doing a pretty good job on his own. "Oh, well, I was invited to speak at the conference. I don't think people invite me to talk in platitudes." I ask why he even thought this might be a witch hunt and he says, "Well, I think most people have written us off." No wonder when he's always having a go. "I give him a gentle reminder about what Act should be about." When I say it doesn't come across as gentle, he says with some enjoyment, "Well, maybe I don't do anything gently."

I think I might trick him into an admission that he's in agreement with Labour on one issue: in accusing Act of sewer politics, but he's too wily. "I'm not even saying that some of the issues shouldn't be raised. Although personally as a politician I would never have done it."

I tell him that I didn't really think I'd manage to get him to agree and he does another of his snorts and takes a free point: "Why would I agree with them when they're doing such a terrible job?"

I have another go at accusing him of helping to push Act over the cliff but he's having none of it. "Nope." Well, Rodney might think he is. "Well, he might. But he's wrong." Does he like Rodney? "I quite like him as an individual. He's quite good company. We're not great mates."

Honestly, he just can't butt out, can he? "Oh, I can butt out." "No you can't. What nonsense!" "Well," he says giving me the triumphant grin of someone who knows he's about to win the match,"if they didn't want to be told what I thought they shouldn't be inviting me to speak, should they?"

He doesn't do a lot of looking back and says "The only thing you have to do is to be able to look in the mirror in the morning and say you did what you believed is right. That's not to say I didn't have some regrets." The regrets are that "If I had my time back again I would have probably tried to move more quickly."

He has never bothered too much about being demonised. "If you were going to demonise anyone you should probably demonise me. I was the strategist. I was the one who did the dreaming up."

He's hard to give hell to because he's had people scream at him in airports, and besides, he knows he was right. You can even suggest he might be out of touch, that politics is a different game now and he doesn't take offence. "It is different, I grant you that."

I suggest, to tease him, that he's jealous of Rodney because he'll never be invited on Dancing with the Stars.

"Oh, my God! I can tell you a story about what sort of dancer I am." This is a story about how when he was at primary school he was the one in the class singled out as singing out of tune. "So that will give you some idea of what sort of dancer I'd be."

It also, I tell him, gives me a nice analogy: he's always been singing out of tune.

"It's just that I sing it a little earlier."

I did enjoy meeting Sir Roger. You can see that he was quite jolly company.

But meeting him was something of a disappointment too. I went to meet someone who was - depending on which way you viewed it - either the hero of economic reforms, or an ogre.

Either way, and he would reject either tag, he has taken on an almost mythical status.

I didn't meet hero or ogre. I met a guy sitting on a bench in a mall with a couple of Lotto tickets in his pocket who can talk about politics until the cows come home. But there are always a few of those kinds of guys hanging around malls on weekday afternoons.