Brand has been good at many things in his 39-year life. He has made people laugh. He has made them cross. He has had a genius for getting into scrapes, womanising, yoga and, more recently, for trying to incite his 8.4m Twitter followers to a peaceful revolution. Now, slightly annoyingly, it seems he could also have been good at writing interviews. His suggested intro is just like the one I was planning. Here is my version.

A black Mercedes pulls up outside a boarded-up shop in London’s East End. Out of it gets a tall man in shades with wild black hair, and a tight, low-necked T-shirt revealing a lot of chest hair.

The diners in the Crisis Skylight Cafe, a co-operative in Shoreditch that helps the homeless find work, gawp. Brand stands on the pavement adjusting tight jeans that are carefully ripped and festooned with chains, and then advances on the café like a large, punky cat.

I gawp too but my wonder is coloured with anxiety. Like 10m others I have watched the Newsnight interview in which Brand charmed, bulldozed and mocked Jeremy Paxman, Britain's toughest interviewer, into laconic submission. This is not going to be easy.

Sure enough, before he has even said hello, Brand has taken control, seizing my hand and leading me, like a parent would a child, into the kitchen at the back. Here, various ex-cons and former drug-users are learning how to chop and fry; he talks to each in turn, touching them lightly. To administer this secular blessing he has to release my hand - a blessing of a different sort as the warmth of his palm was making me feel very uncomfortable indeed.

“I need a pee,” he declares when he has finished with the kitchen staff. He disappears leaving me to wait with a growing band of excited diners; when he emerges, he grants some selfies, then strikes up a conversation with the café manager. Brand is planning to open his own co-operative with the profits from his new book, he says, and wants advice.

I hop from one foot to the other and eventually protest that I am meant to be interviewing him, so preferably need him on his own.

“That’s a very capitalist and selfish attitude, Lucy, very individualistic,” he says, looking straight at me. But obediently he goes to sit at the only empty table, while I queue for the leek and potato soup and red juice he has asked for, ordering the same thing myself.

Does he read the FT, I ask, sitting down opposite him at last.

“No,” he replies, leaning forward so his face is very close to mine.

I say he ought to. He has just written a book in which he argues that capitalism is over, and at the very least he ought to know his enemy.

“I find it hard to understand. It obfuscates truth and I think an economic ideology is oppositional to the spiritual ideologies that are what we need to adopt if we’re to save our planet and humankind. Capitalism, the economic arm of the individualism and materialism ideologies that keep us framed in a narrow bandwidth of consciousness, prevents us from seeing that we’re all connected.”

On the page the words are, at best, a bit of a turn-off. But listening to him talk you don’t hear them; instead, you see his eyes boring into yours, his body wired into a posture of absolute belief.

I protest that capitalism has lifted billions from poverty in his lifetime.

“Yes, I’m sure a lot of people would prefer waterboarding to anal rape but we don’t have to tolerate either,” he replies, slightly bafflingly.

A girl with a pierced tongue brings our soup. “How’re you feeling, mate?” Brand asks her. “I’m star-struck,” she says and explains that she’s had some problems and that she’s just had her electronic tag taken off. She says she wants to go into hospitality. Brand assures her that she will do well, and she flushes a deep red.

When she goes, his eyes light on a proof copy of his book, Revolution, which I’d brought along as I wanted some of it explained to me.

“I love this book!” he says, touching it fondly. I say I only loved some of it. I read him a bit I’ve underlined: “The economy is just a metaphorical device, it’s not real, that’s why it’s got the word con in it.”

“People like shit like that,” Brand says, evidently enjoying the reading.

But it’s nonsense.

“My darling, tell that to the people that are suffering. You can’t ignore the argument that all around us there’s poverty. Ordinary people can’t afford to live in this city.”

He could not have chosen a better place from which to make this point. The Crisis café is barely a mile from the City’s banking skyscrapers and the contrast is ugly.

As Brand holds forth on the evils of capitalism, I get the feeling that I'm talking to a clever, intransigent teenager, the only difference being that Brand has a frighteningly large audience for his blend of tosh and truth. Ten times more people follow him on Twitter than follow the prime minister David Cameron, and his political YouTube channel, The Trews (True News), though maddening both in its title and in its hectoring content, is persuading apathetic youth to feel cross about the state of the world. My son's a fan, I say.

“Good!” he beams showing both top and bottom decks of teeth.

I tell him that though it may be good to make the young feel outrage, it’s less good to tell them not to vote.

He seizes my hand and holds it firmly.

“My voting thing is not an allergy. The reason I don’t vote is the same reason I don’t eat glitter; there’s no fucking point.”

In his view, only the Scottish referendum was worth voting for.

"Do you know why I think the people of Scotland should have voted yes? Because Cameron wanted them to vote no. Do you know why I think we shouldn't be bombing the Middle East? Because they want to bomb the Middle East. Any single thing they tell me, I disagree with absolutely 100 per cent."

I try to protest at the babyishness of this stance but Brand is in full rant.

“I would suggest total disobedience, total non-compliance and also total organisation! Don’t just stop paying your taxes and mortgage on your own, find a group of people to not pay mortgages with you!”

That’s all very well, I point out, only it will bring on a catastrophic recession that will most hurt the very people he is trying to help.

Now he grabs my other hand too, which makes it hard to argue back - and harder to eat my lunch.

“Shut up, Lucy. You’re only thinking within very narrow parameters. This planet - there’s a number of people, there’s an amount of resources, we need to make sure that people get resources. What’s the reason that we’re not doing that? The answer is because of the ideology that you’re propping up.”

He stares accusingly, as though the whole problem with capitalism were my fault.

I point out that I’m not the only one propping up the system. What about Brand’s chauffeur-driven Merc outside?

He replies that his chauffeur, Mick, is a really great guy and a friend - which is nice but not the point. What about the beaded necklace, which looks suspiciously like amethyst, that is dangling down towards his soup bowl? How much did that cost?

“Who knows?” he replies as if this were an unfathomable mystery. “I’m not interested in making money any more.”

Does that mean that there will be no more acting, no more Hollywood?

Brand pauses. “It probably does mean that, yes,” he says, hesitantly, as if making up policy on the hoof. But he’s not going to quit comedy, he says, because he loves performing. When I ask how lucrative it is, he shrugs.

“It makes me scared if I think about money too much, then it makes me feel guilty. The only thing I tell the people who look after my money is, ‘Make sure my fucking taxes are 100 per cent legitimately paid,’ and then I do my own shit.”

But isn’t he against taxes? “Only as part of a mass movement, not as tax evasion,” he says.

Surely he can only afford to do his own shit because he is so rich. Would he really be prepared to give it all up?

“I’d give up everything. I’ve thought about this a lot, whether or not I’m prepared to go to prison or die for what I believe in. The answer is 100 per cent, without question, yes, I’m willing to die for this.”

If you really believe that, I say, that makes me think you’re nuts.

“Well, that makes me think you’re nuts because you’re going to die as well and when you die it’s going to be for nothing, an unremembered, pointless death, propping up a dead system!”

At this point we are interrupted by an emaciated woman strolling off the street requesting a selfie. Brand embraces her as he takes the picture and, catching the whiff of fags, tells her to cut back. She glances at me and asks if I’m family.

“We’re on a first date,” Brand explains.

The woman looks a bit surprised and scuttles off.

It occurs to me that the main difference between me and my guest is not our approach to economics but to human nature. I, who have mostly led the life of a goody-goody, believe people are fairly selfish. Brand, who has been bad more than most, thinks people are good at heart. How does that work?

“Because I believe in change. Because I’ve seen a revolution in my own life, I’ve come from a very ordinary background and I’ve become a drug addict, I’ve lived for years on benefits and now I live a completely different life where I experience all of the glamour, all of the things that capitalism promises - fame, pop stardom, glory, money. And it’s worthless and it’s meaningless.”

Just as I’m protesting that not everyone can change, a man who appears to be shaking drags himself into the café. He is clutching a very tatty copy of the Big Issue.

“How’s your habit?” Brand asks him, fishing in his pocket and taking out a note, which he squashes into a tiny ball so neither I nor the hapless recipient can see how much it is, and hands it over.

Will that man change, I wonder. And should he be giving money to him before he does? “I always give money to drug addicts. It is a necessary reprieve. No one stops taking drugs ’cos they’ve not got money - they will steal.”

In the hour we have been together, Brand has not only made the junkie’s day. The comedian has made everyone he has touched glow with an almost indecent pleasure. When I remark on this, he beams again. “That makes me feel so happy and worthwhile.” In a way this is sweet but, equally, one wonders who needs whom more: the disciples the celebrity, or the celebrity the disciples.

The only person I can think of who comes close to Brand in terms of the effect he has on others is Bill Clinton; if the two were together, I suspect the comedian would make the former US president look gauche by comparison. Perhaps it shows that Brand's true vocation is more politics than comedy. Come the revolution, will he be its Lenin?

“I went into this thinking, ‘Me with my charisma and my belief system, I should be in charge of this whole shebang.’ But I realised that you don’t need any show-off mouthing off at the front, you need people to have control of their own destinies.”

In Brand’s revolution there is no place for leaders or individualism of any sort. Which might be sensible, except the message is delivered from a platform built entirely on his own celebrity and egotism. In the book he only gets down to telling us what the revolution consists of after 80 pages devoted entirely to Brand on Brand.

“It’s only 80 pages, for fuck’s sake. When you’ve written a book I’ll critique it. Shall we have another juice? ”

I get up to order the drinks. When I get back, my guest has gone.

"I'm enjoying this," he says when he returns. "I used to do interviews where I'd just talk about Katy Perry. "

I tell him that most business readers have never heard of his former wife, though they have heard of his more recent girlfriend - but, as I try to name her, my mind goes terrifyingly blank. After a few seconds the name reappears in my mind: Jemima Khan.

“Took you a while to remember,” Brand says. I tell him it’s old age.

“You’re not old. Well, I’ll tell you this; I think you’re a very beautiful woman. There’s moments when you spasm into apoplexy where you’re quite delightful.”

I try to ignore this shamelessly transparent attempt to avoid the question and ask again about Khan.

“Oh, I’m not talking about all that claptrap.” He waves dismissively.

I try another tack. In his life Brand has overcome most of the addictions available to mankind but the two he has yet to master are sex and fame. Which of these is harder to kick? “I don’t think you kick addictions. I really feel for people that have eating issues because you’ve got to unlock your addiction at least three times a day. I think sex is a comparable behaviour, isn’t it?”

Is he saying that people generally have sex three times a day?

“Well, no. Some days you have to hold it down a little bit,” he replies, deftly deflecting the question with a joke. But on fame his response is more telling.

“I am, as you have said, a bit of a show-off. As long as I don’t spend all my time focusing on that aspect of my nature that’s about showing off, and if I can try and make that work for the common good, that’s not such a problem, is it?”

The waitress returns to take our plates. “That was bloody lovely,” says Brand, hugging her while she takes a picture of both of them.

The café is closing and I am the only person in the place who has not demanded a selfie with the do-gooding narcissist, a situation he evidently thinks remiss.

“Your boy’ll want a photograph, won’t he? I think he’ll want us to be having a mouth kiss.”

I assure him my son won’t want any such thing but Brand is already coming over to my side of the table, putting an arm around me and moving his lips towards mine, while I swerve out of reach. After this embarrassing little skirmish I ask if it is the first time a woman has cringed as he tried to kiss her.

He shakes his head and insists I didn’t cringe. “Your body language looked halfhearted and your face changed colour.”

When I get home, I look at the pictures on my phone. Paxman couldn’t help himself when faced with this charismatic, ranting revolutionary and neither, it seems, could I. The camera doesn’t lie. I am blushing and smiling as I duck.

Lucy Kellaway is an FT columnist.

(c) 2014 The Financial Times Limited