THE ROGUE TRADER: NASSIM NICHOLAS TALEB

Taleb, 48, predicted the current global financial crisis in his book The Black Swan: The Impact of the Highly Improbable. He is an applied statistician and derivatives trader-turned-philosopher.

I predicted the current global financial crisis in my last book, The Black Swan. You might well ask why more people didn't see it coming. Well, there are some situations where the outcome is predictable – if you board a plane being flown by a drunk pilot, it's significantly more likely to crash. But there are rarer events, such as the current financial turmoil, that have complicated probabilities we can't compute. The problem comes when people make claims about these probabilities; what they say may sound convincing, but the point about these probabilities is that it's difficult to offer any sort of certainty. The disastrous results can today be seen in financial markets the world over.

My predictions have been built on a philosophy I have preached for two decades: That we should avoid risks we don't properly understand. We have always based our actions on what we think we know. I'm trying to reverse this philosophy, to encourage people to make decisions based on what they don't know. No one believed that black swans existed until they were found in Australia, which is why I borrowed the term for exceptional, unpredictable events.

As we survey the wreckage of the world's financial systems, this philosophy may sound obvious. But, until recently, I was a lone voice. I tried to pursue my thesis in academia but I realised I was an outsider. Fortunately for me, I was also a trader in the stock markets. Those traders who were betting on market stability and growth found it easier than I to attract investors, but nevertheless, in 1987 I managed to derive enough income from the stock-market crash of that year to be independent for life.

Despite now feeling vindicated in my beliefs, I harbour a lot of bitterness. I wrote in The Black Swan that you need a constituency around you to share your opinions, and I didn't have that in my academic pursuits. But that's what happens when you try to tell people the sky is blue and they're convinced it's yellow because they read it. Interestingly, I didn't suffer much from public attacks; rather, I received huge amounts of hate mail from the economics establishment. But it convinced me that I was right.

Before I wrote Fooled by Randomness in 2001, I was presenting my ideas in ways that were inaccessible to a broad readership: Academic papers stay within a small community. But my isolation forced me to present my ideas in a book.

People think that being embraced by others for your beliefs shouldn't matter – let me tell you, it's exhilarating. If I'm beginning to sound like the sort of figure I've spent my career criticising – the guru – there's a key distinction: I say listen to negative rather than positive advice.

When you go to a book shop there are plenty of publications telling you how to get rich, but none telling you how not to go bankrupt. To put it another way, if you want to get rich, avoid being poor. Negative advice is more robust than positive advice; it is rarely respected, though, unless you present it in a digestible form.

I haven't been surprised by the past few weeks of financial turmoil. I warned about a bail-out. But nobody likes to be reminded of this.

I don't know if I'm a visionary; I'm just someone with a consistent view of the world.



THE CRASH SURVIVOR: PETER HAMBRO

The 63-year-old is a scion of the famous Hambro banking dynasty. He is Executive Chairman of Peter Hambro Mining, the second-biggest gold producer in Russia, and has warned against the dangers of financial derivatives for over a decade.

My father was in the gold business before me; the stuff flows through my veins. Gold is a proven long-term store of value, if you own an ounce you wouldn't have to worry which bank it is in; you'd have it in your pocket.

When I left gold trading and bought a Russian gold mine 15 years ago, people said I was mad, but I invested in it partly because I thought it would make a lot of money and partly because I was terrified about a collapse in the financial markets. I have always thought that the lack of regulation in the mark-to-market derivatives industry in the mid-1990s was a recipe for disaster. I wrote to the Governor of the Bank of England to tell him so. I felt that Gordon Brown's sale in 1999 of half of the country's gold reserves at $256 an ounce was an error. I became convinced that the country's gold would be needed as a reserve asset and that its price would rise, and I've been proved right – gold has gone from $300 an ounce a decade ago to $830 an ounce now.

I was lucky enough to have family members old enough to have lived through the crash of the 1920s and so to have discussed this with them. Perhaps for that reason I had a stronger feeling than most that things were going wrong.



THE HI-TECH GODFATHER: JIM WESTWOOD

From 1963 to 1990, Westwood, 60, was Sir Clive Sinclair's right-hand man, and the inventor of the first pocket calculator, the first portable, flat-screened television and the first affordable home computer, the ZX Spectrum.

The first thing we wanted to do was make a tiny TV. From 1964 that was the burning ambition. We exhibited one at a trade fair in 1966. It went to prototype, but it was before its time.

We could design it, but could we mass-produce it? No.

We launched portable televisions in 1973 and 1978. The first one was around £200 (Dh1276) and the second more than £100 (Dh638) but we needed a price nearer £50. The final throw of the dice was in 1983. That was a flat-screen television using a flat cathode-ray tube – but the tubes we intended to manufacture for £2 each actually cost £10 each.

That was a problem. It was impossible to get the price low enough. We'd worked on televisions for 20 years and I thought I had it cracked, so it was a bit sad.

But we'd already started to do something else: Computers.

The ZX80 and ZX81 were the first computers. They were very successful. The ZX Spectrum sold 3.5 million units. We wanted to produce a tool to help people understand computers. Instead, people played games on them.

Out of 20 ideas we had, three would hold water and one would make it. My favourite idea was the pocket calculator. I had found a way to reduce the energy consumption to a 30th of existing calculators, so you could have smaller batteries.

The Sinclair Executive was the first pocket calculator, but by 1979 we had moved out of calculators: The Japanese made it cheaper to buy a complete calculator than buy its components and assemble it in Europe.

And that is what my life has been like with Clive; making a brilliant idea saleable. You find a trick but other people will catch up with it. It's always a race.



THE KEYHOLE PIONEER: LORD ARA DARZI

Born in Iraq, Darzi, 48,emigrated to Ireland at 17 to study medicine, before moving to London, where he began his work on keyhole surgery in 1990. He still conducts operations at St Mary's in London.

I developed the keyhole technique during an era when, from a surgical perspective, the bigger the incision, the more macho the surgeon. I recognised that an incision was probably the biggest component of pain for a patient, so what was driving me was how to reduce that. I started with keyhole operations for gall-bladder surgery and you could see patients recovered much quicker. I had a lot of critics so I had to turn them around. You bring people with you not by saying "because I say so", but by taking them through the entire process. I worried I'd be singled out as a maverick, but I always remembered why I was doing it: Not to be different but because it had an impact on patients. I pushed the boundaries in using keyhole surgery. The more I wrote about the subject, the more patients expressed a desire to have the procedure done that way and 15 years on, it has become common practice. 

- By Robin Barton, Kate Burt, Rhiannon Harries, Mike Higgins, Adam Jacques and Simmy Richman (The Independent)