Philosophy being one of the Ps in Oxford's PPE curriculum, as well as politics and economics. Harford enrolled in the course because it was that or law. "Though I was thinking maybe I should study law. I really had no idea. The student who showed me around the college said, 'Well, the talks for law and PPE are at the same time'. I stood there indecisively, and he said, 'You certainly don't want to study law, mate'. So I said, 'Fair enough'."
Harford, I should mention, has written three books, writes a regular Financial Times column and turned a TV series and a radio series into a career as a popular economics pundit. His fourth book, The Undercover Economist Strikes Back, has just been published.
His self-deprecation is pleasant and well-practised, but you might suspect he overstates the extent to which he has backed into his success, although he makes a good case for the importance of luck in most areas of life, economics included.
"Which is not what we are told. As we go through the education system, we're told that it's all about hard work and talent. And yeah, talent is important, hard work is important.
But one thing I've discovered, studying the economy, is there's a lot of luck involved in doing well."
Studying the economy was in itself a bit of luck for Harford.
"I very gradually realised that I didn't want to drop this subject. I found it more and more fascinating." Another was meeting the right person at the right moment and being nudged into realising he didn't need anyone's permission to try his hand at writing.
"I'd tried being a management consultant. I was a terrible management consultant. I lasted only a few months. I was wearing a suit for the job and I developed an allergy to it.
It was bringing me out in a rash. One of my colleagues said to me, 'Tim, you only need to be able to do two things to do this job, wear a suit and talk bullshit. And you can't do either of them'."
He moved on to Shell's long-range-scenario team, a multidisciplinary group tasked with generating provocative visions of what the world might look like decades from now. "Oil companies make very long-term investments."
David Bodanis, who had unpacked Einstein for non-specialist readers in his best-selling E=mc2, was brought in to consult on trends in technologies.
"David and I had been hanging out in Starbucks for about a week, and I said, 'I really wish I could write a book like E=mc2, only about economics.' He kind of looked at me. He talks a lot, really, really fast. But this one moment he didn't say anything, he just gave me this look: 'Go on, keep thinking.' And I realised, 'Oh. Oh yeah. I could just do that'."
That was 2001. Harford started writing The Undercover Economist more or less immediately. It was finally published in late 2005.
"I don't quite have a J.K. Rowling story of constant rejection, but actually there was quite a lot of rejection. It took a long time to get published. Then I never looked back. It was partly because Freakonomics [by Steven Levitt and Stephen Dubner] had just come out. That book sparked this tremendous interest in economics."
Suddenly, Harford had a book coming out in America and Britain, he was offered a chance to present a TV series, Radio 4 asked him to present a show, and he sold a column based on the book to the Financial Times.
"I now realise it was completely ridiculous good fortune. I was very very lucky. But then my follow-up book was all about how people are far more rational than you think they are, and it came out in the middle of the financial crisis, just as we were seeing how utterly irrational people can be. You know, you've got to enjoy the rough with the smooth."
"Macroeconomics" - the study of the economic system as a whole - "is a flawed subject.
That, in essence, is because it's a very difficult subject. I've studied it both as an undergraduate and as a postgraduate, and I always felt I was a step behind.
"Writing this book at first felt like a duty - 'how can I not write about macroeconomics?
It's so obviously important, it's been the big issue for six years, it's an obvious sequel to the first book, I've been putting it off, I should do it.'
"But it drew me in. It's really fascinating. And they're not as stupid as they sometimes seem, macroeconomists - they're trying to do something really, really hard. There is a method behind the apparent madness, which I think I eventually figured out."
Harford opens the book with the moment a group of London academics first saw what an economy would actually look like if you could model all of it at once. It was 1949, the world was recovering from World War II and the Depression, and there was a real push to understand how depressions could be kept from happening again.
But it had never occurred to anyone that you could demonstrate the flows and the turbulence of such a complex system using a bunch of plastic tanks filled with water and strategically interconnected with dams and sluice gates. Then a New Zealand farmboy with no formal education showed up at their door and demonstrated that it could be done. His name was Bill Phillips, and he became one of the great economists of the last century.
"I'd known about the Phillips machine for a long time - it's a wonderful visual metaphor for the macro in macroeconomics.
"The idea that there are these flows and they all fit together. I always planned to start the book that way. But economists - we're slightly awkward people, we don't really talk about personal stuff, so I'd never heard any of the stories about Phillips. As I did more research I started to hear snippets of this amazing life.
"Actually, there's a lecture on YouTube by Alan Bollard, the former governor of your Reserve Bank - it's a little dry in the delivery, but he's a central banker and they specialise in dry. But it seemed like every minute this amazing fact would drop, deadpan, out of Bollard's mouth.
"Bill Phillips had the most astonishing life. Finding out there were all these amazing stories to tell was a gift."
The Undercover Economist Strikes Again (Little, Brown $39.99) is out now.
