HARVARD professor Niall Ferguson specialises in financial and economic history, which is the subject of his latest book, The Ascent of Money.

Born in Glasgow, Ferguson, 44, has also presented a number of television series based on his books, including Empire, on the rise and fall of the British Empire. His Channel 4 series on The Ascent of Money starts tomorrow night.

Ferguson divides his time between his Oxfordshire family home and his house in Boston. He is married to Sue Douglas, a media consultant, and has three children: Felix, 14, Freya, 13, and Lachlan, 9.

How much money do you have in your wallet?

Let me just have a look. Right now I have £10, 35 Canadian dollars and 255 US dollars. I travel a lot so I generally have at least two currencies on me at any one time.

The Scotsman in me tries to minimise my cash balance because it is not an especially good asset to have in this inflationary world, but I have learnt that having some cash on you is useful when you need to get a taxi.

Are you a cash or a card person?

I will use cash or cards according to the circumstances, but always with a sense of reluctance. I intensely dislike spending money, which means that I love big conferences where somebody else pays for everything.

Are you a saver or a spender?

I am definitely a saver. Staying in cash seems like quite a good idea at the moment, while the markets are going crazy, as long as you are earning a reasonable amount of interest on it. Generally speaking, I also find a positive account balance very satisfying. I am in debt overall, but that is because I am married to a spender. And all our debts are set against assets, in other words, our three houses.

How much did you earn last year?

I will take the Fifth Amendment on that if I can. It was north of seven figures, but not by much. Suffice to say that in Britain I would be embarrassed that it was so much, and in the US I would be embarrassed that it was so little.

How much was in your first pay packet?

I was a junior fellow at a Cambridge college at the time, so it was probably not very much at all. I think my annual salary was about £12,000.

Have you ever been really hard up?

Yes. Once, when I was a graduate student living in Germany in the mid-1980s, I completely ran out of money. The only way I could get money to eat was to go into a jeweller’s, buy a wedding ring with a credit card that was over its limit, and then take it straight to a pawn shop. I used the money to buy as much bread and as many carrots as I could, because I figured I could survive on that. As I ate my carrot sandwich that night, I decided that I never wanted to be broke again.

What is the most lucrative work you have ever done? Did you use the fee for something special?

It would probably have to be the consulting and advising work I have done for investment banks and hedge funds. In the glory days of 2006, demand for a historical financial perspective was very high and there was a point when it was not impossible for me to get 100,000 US dollars for a one-hour speech at some extravagant hedge-fund manager conference in an exotic location.

I used the money from these appearances in a vain attempt to reduce my debts by paying off the mortgage fund.

What property do you own?

The family headquarters is a farmhouse in Oxfordshire that we bought a long time ago. We also own a small house in Boston, which is where I live when I am teaching at Harvard, and a holiday home in Wales.

Do you invest in shares?

No, I cannot afford to, what with all these bloody houses.

What do you think about the markets at present?

We are in the midst of a very serious financial crisis. It is as big as anything since the Great Depression. So you would have to be very brave to call the bottom of the equity market now.

With regards to property, I think that a lot of people in Britain became convinced that property prices could never come down and loaded up on debt to get on to the ladder as a result.

That is one of the main reasons why the country is in trouble now and why it is so serious.

What’s better — property or pension?

This is the crux of a long-standing argument between my wife and me. She prefers to invest in property, but I think it is looking a bit more like going my way at the moment, especially as the taxes you pay on capital gains from property wipe out a lot of any profits made.

The correct answer however is, of course, both.

Are you financially better off than your parents?

Yes. My father was a doctor working for the NHS, and my mother was a teacher, so I had a very middle class upbringing. But the 1970s, with its pay freezes and double-digit inflation, was a very difficult time for the British middle classes.

I was always very aware of the financial pressures on my family growing up, and the first thing I ever had published was a letter to the Glasgow Herald, complaining on my parents’ behalf about the cost of my shoes. I was 10 years old at the time.

What has been your worst investment?

I think that would be the holiday home in Wales. We bought it at the top of the property bubble for £900,000 and I am sure the value has dipped since then. It is a beautiful 16th-century property on the coast near Porthcawl and is a wonderful place for holidays, but in financial terms — ouch!

And your best?

It would be another property — our family home in Oxfordshire. We bought it in the house-price trough and, although I cannot remember exactly how much we paid, I think it was worth about four or five times the amount we paid before the recent housing sell-off began.

I am sure that it has come down in value since then, but it is a very well located house, so I doubt it would lose too much.

What aspect of our taxation system would you change?

That is a very good question. I would prefer to have a very simple income-tax system with a single rate, and to increase taxation on consumption. I believe that this approach would reduce pointless bureaucracy and encourage saving, which is something the UK government really needs to do. Double taxation is obviously nuts, too.

What is your financial priority?

I am very risk-averse and would therefore love to move to a less leveraged balance sheet — I dream of being debt free. I would also love to be high net worth, with the emphasis on the net.

Do you have a money weakness?

I worry about it too much. I am a very ascetic person and essentially prefer the feeling of not buying something to the feeling of buying it. The idea of a shopping trip makes me feel physically sick.

What is the most extravagant thing you have ever bought?

My wife and I tend to compensate for the fact that we are apart a lot and work so hard by having quite expensive holidays. We have had two high-end Kenyan safaris in the last few years, both of which cost about £10,000 for a week.

What is the most important lesson you have learnt about money?

That it is not the most important thing in life, although it is close. Not having any money really is everything. Ask anyone who is really poor.