I thought it would be at least pudding before Darius Guppy would reveal what Boris Johnson calls his "Homeric code of honour, loyalty and revenge". But barely five minutes into lunch he is offering to beat up Andrew Neil, who once sacked me. How kind! We chink glasses and laugh, a bit too hard in my case. He's joking, of course. Or is he?
Guppy is a self-diagnosed "potential psychopath", and has the charm, intelligence and good looks to prove it. He has form on administering beatings, once giving Charles (Earl) Spencer a broken cheekbone for allegedly trying to seduce his wife. Then there's the taped conversation with the now mayor of London, in which he asks for the address of Stuart Collier, a tabloid journalist who displeased him ("How badly are you going to hurt this guy?" quavers Boris).
Charles, Boris and "Darry" were thick as thieves at Eton, Oxford and the Bullingdon Club, though only Guppy actually went on to steal £1.8m in an insurance fraud, rounding off his education with three years at Her Majesty's pleasure, "a natural progression", he calls it.
Fifteen years after his release, I find him sitting in a pink shirt and slick hair at the best table at L'Escargot in Soho. He insists on paying, and begs me to order beluga caviar and lobster, "so that you don't stitch me up". He is a master of flattery, and likes to make conspiratorial suggestions, inviting me to rob a bank with him. When we leave, he offers me a job in Iran, though he can't say what as.
But first, we are here to discuss an essay he has written, outlining his solution to the economic crisis. The Independent on Sunday has agreed to Guppy's condition to granting this, a very rare interview, that we publish his essay online. That Darius Guppy thinks the world should pay attention to his views on the global economy is a measure of the confidence an upbringing like his can give you. And while, for most of us, a convicted fraudster would not be the first port of call for guidance on where the world is going wrong, his argument does reflect a growing impulse among economists, and one that runs strongly counter to the gas-guzzling assumptions of much of his social milieu. He says we should stop assuming that economic growth is necessarily a good thing, as the planet is a finite resource.
"While my views may be controversial, I can assure you that they are by no means nutty," he says. "If, for example, you Google names such as Richard Douthwaite, Herman Daly, David Korten, Margrit Kennedy, Donella Meadows, Joseph Stiglitz, and so on, you will quickly appreciate that there is a highly respected body of academic opinion out there which would concur with my arguments. It is the notion of continued exponential growth in a limited world, the assumption on which our politicians' remedies are all based, that constitutes the real madness, and I find it remarkable that the mainstream press seems oblivious to this basic piece of common sense."
As far as Guppy is concerned, you suspect the interest of most of the press, mainstream or otherwise, is in his current shadowy (or at least not well publicised) existence. It's the first time, for example, he has spoken since his Eton and Oxford contemporary David Cameron became prime minister, and he makes an odd alliance with the Archbishop of Canterbury in attacking him and the coalition for their lack of ideas. "Cameron studied PPE at university – politics, philosophy and economics. I'm underwhelmed with his politics and economics, but on philosophy, he hasn't even turned up to write the exams."
Guppy calls for a stronger moral, philosophical and religious underpinning to politics. "It is mystifying to me that politicians, quite a number of whom I have known from my own and my parents' generation, are so unimaginative and parochial in their approach to the problems that face us." He says capitalism has corroded society in the past 30 years, bankers are "crooks", and the Conservatives under Margaret Thatcher are to blame for creating the "broken" Britain Cameron speaks of.
Guppy now lives in South Africa with his wife of 20 years, Patricia, and their three children. He spends much of his time on business in Iran, where his mother, the late singer and writer Shusha Guppy, was born. He refuses to elaborate on his business, saying only, "I am a globe-trotting man of international mystery". What, an arms dealer? "I am not an arms dealer. I trade with the Middle East with a particular focus on Iran. Buying and selling things." Like what? "Put it this way – if we were to go to war with Iran, I would be in trouble. But I know which side I would be on."
This is an allusion to his faith (he is a Muslim) but also a reference to his disenchantment with Britain, which he believes has suffered through the decline of religion. He remains a supporter of Christianity, the faith in which he was raised, and he would not want Islam to supersede it; but he believes George Bernard Shaw was right to predict that Islam will prevail, saying France will be first to capitulate, "within a generation".
The problem with secularism, he says, is that it fails to provide an alternative moral framework, causing a worsening of the human condition. "In the West, money has replaced God as an idol. Money is now pursued as an end in itself, as against the means with which to lead a happy life, and this has caused our economic problems." He praises this newspaper for the publication of the Happy List, a challenge to The Sunday Times's annual celebration of wealth, the Rich List. Success, he says, should be measured by happiness, not money.
"Never has there been so great a discrepancy between rich and the poor," he says, "Bankers can earn one thousand times a normal salary. The rich men of the past were never that much richer. If you grow up on a sink estate, you're being programmed to think that unless you have the latest Maserati and a girlfriend like Jordan, you are an inadequate, and you feel trapped."
Guppy was born in 1964, not on a sink estate but with all the privileges anyone could wish for: wealth, connections and intelligence. His father was the writer and explorer Nicholas Guppy, and he grew up in intellectual circles, witnessing vigorous debates around their Cambridgeshire table. He is a talented poet, his work having been praised by the critic Christopher Logue. Through his mother, he learned about the teachings of Islam, and calls himself an old-fashioned Muslim. "Religions, by their very nature, look back to better times. If you are religious, it is likely you will be engaged with the past." He calls himself a traditionalist, and says Western culture has been in decline for nearly 200 years, since the early 19th century. "Health is the one area where there has been an improvement. But in culture there has been a huge decline since the Enlightenment, aggravated by the rise of secularism and the decline of morality."
Although he has a fierce moral code, it doesn't trouble itself with such trivialities as the law. God, he says, is the only true judge. And because of this he sympathises with poor people who turn to crime – it is a natural consequence of a society divided by enormous gulfs of wealth. "I wouldn't join a bank, I'd rob it. If you have that sort of energy in you, you go and do it."
He certainly has no regrets, not even of prison. "I'm not going to do a Jonathan Aitken and flagellate myself," he says. "But I don't want to glamorise it, and pretend it was a bed of roses, because it wasn't. But it was a bit like university – you go up thinking everyone is going to be fascinating, and they're not – about 10 per cent are. What you find in prison is that a higher proportion of people inside are very brave, courageous and imaginative people. They are prepared to take a risk, and in a different context would be building Britain's empire. I liked that energy."
Guppy and an Oxford friend, Benedict Marsh, were convicted of faking a jewel robbery; they paid a third party to tie them up and shoot a mattress in a New York hotel room. It would have been the perfect crime had an informer not grassed them up.
In 1989, Guppy was the best man at Spencer's wedding to Victoria Lockwood at Althorp, at which Princes William and Harry were page boys. This Saturday, the earl will marry again at Althorp, but Guppy is not invited. He does not regret stamping Spencer out of his life, who "crossed a line" in their 30-year friendship. It was Spencer who loaned him a farmhouse rent-free at Althorp when Guppy was released from Ford Open Prison in February 1996, before he moved to Ireland. There he bought and sold property, benefiting from the boom and doubling his money on a Georgian mansion in Tipperary.
He remains in touch with his Oxford friends (the ones who haven't crossed him), though he hasn't seen Boris "in years". One suspects this is more of Boris's choosing than Guppy's. They are in email contact. He says he prefers not to see his old friends: "I don't want to think that they sold out, that they became boring," he says. "I don't want, when I have lunch with them, to think, is there a tape recording, am I going to be snapped? It is a shame, but I have such fun memories of these people that I would rather preserve those memories."
Before we leave, he asks if I've ever swum with sharks. It's one of his favourite hobbies in South Africa, that and big-game hunting. He tells me of an occasion when a great white shark attacked the cage he was in, its nose rammed between two bars, inches from his face. "It's incredibly exciting, you should try it." Tempting as it sounds, lunch with Darry is probably close enough an experience.
1964 Born in London to Nicholas Guppy, the writer and explorer, and Shamsi Assar, better known as Shusha Guppy, the Tehran-born singer and writer.
1975 His parents divorce, though they remain friends and neighbours in Chelsea.
1977 Attends Eton; becomes friends with Boris Johnson and Charles Spencer, brother of Diana, Princess of Wales. 1982 Goes up to Magdalen College, Oxford, to read history and French.
1983 Becomes a member of elite drinking societies, such as the Bullingdon.
1986 Graduates with a first. (Johnson gets a two-one). Given his first job by fellow OE and Ministry of Sound founder James Palumbo, as a butler in Hollywood.
1989 Is best man at Earl Spencer's first wedding.
1990 Sets out to beat up a News of the World journalist, Stuart Collier, whom he suspects of trying to smear his fiancée. Enlists Johnson's help.
1991 Marries Patricia Holder, from Sunderland, whom he met at the Groucho bar. Spencer is his best man.
1993 Convicted of fraud and sentenced to five years. His wife is pregnant with their first child, Isabella.
1996 Released from Ford Open Prison. Publishes his memoirs, Roll the Dice. They move to Ireland then Constantia, Cape Town.
2000 They have twins, Lorcan and Edmund.
2008 His mother dies.
2009 A recording of his conversation with Johnson about Collier emerges, embarrassing the mayor. Guppy's only remorse is that he didn't finish the job.