Harford is smart. Scary smart. So smart he can illuminate, in clear, entertaining English, ideas and forces of mind-boggling complexity.

So when filming an episode of his June BBC2 series . . .working title 'Trust Me, I'm an Economist' . . . the author and Financial Times columnist didn't hesitate when asked to give a medallion man some advice on pulling: think of yourself as a DVD player.

It looks good, but you see if the manufacturer offers a money-back guarantee, " he recounts to the Sunday Tribune in the Merrion Hotel while on a swing supporting his number-one Amazon bestselling tome, The Undercover Economist. ?This sends two messages. One, I'm safe.

Two, the manufacturer expresses confidence that you won't ever need to bring it back."

He gave two tickets to a top West End show to Medallion Man and told him how to use them as his own moneyback guarantee with a prospective girlfriend.

All very interesting. But what does this have to do with money supply, interest rates or the Dublin housing market? You know. Economics.

Harford tells me about his time lecturing in economics at University College Cork 10 years ago. His students, many older than his then 22 years, were divided between those who wanted to be social workers and understand the evils of capitalism and the business students who wanted to become masters of the universe by studying his arcane art.

Both were wrong. Economics isn't all about money.

It's about everyday life and the things going on all around us."

I see a cup of frothy coffee.

Harford sees a global supply chain of commodities and expertise. He also sees the menus at Costa Coffee or Cafe Sol as tools to sniff out those consumers looking for a reason to part with more of their money.

Coffee features a lot in Undercover Economist. (His favourite is from Timor. ) He translates items from a London Starbucks with their escalating prices, like the £2.49 White Chocolate Mocha . . . Use different powder . . . I feel very special" . . . and the £3.09 Venti verstion . . . ?Make it huge . . . I feel greedy".

He explains: ?By charging wildly different prices for products that have largely the same cost, Starbucks is able to smoke out customers who are less sensitive about the price. Starbucks doesn't have a way to identify lavish customers perfectly, so it invites them to hang themselves with a choice of luxurious ropes."

That's from the book, and it's a credit to Harford that he writes as he speaks. Whether about the economics of traffic congestion, health care, the environment or the rents on marginal scrubland the theories of 19th century English economist David Ricardo.

'How China Grew Rich' is the book's last chapter. Should we worry that the West is destined for poverty as China draws in metal and rocks and oil and cash and whole industries like a black hole? Harford's having none of it.

Even if you were to 'shut down' trade with China, " he snorts, making clear how likely that is. ?China is lifting a million people out of poverty each month. Never before in human history has that happened. Can you justify stopping that?"

What about immigration?

Working-class people worry that when working-class immigrants arrive wages will be kept low. Middle-class doctors or teachers tut about that, but when immigrant teachers or doctors arrive, suddenly it's, 'isn't it wrong for us to take their best people?'

People are remarkably good at identifying their own economic self interest."

How did Medallion Man get on in the end?

He didn't get it. I told him to give her the tickets for the show a month in advance.

They're hers. Then to say, go on a date with me. Maybe two.

The tickets are yours in any case but I'm so sure you'll like me if you get to know me that I'm betting you'll want to invite me to that show."

Instead he offered them to her as a bribe to go out with him, like a pimp."

Maybe economists should stay away from dating advice after all.