I have hired quite a few finance directors over the years. Some were outstanding; others did not work out so well. Inevitably, I have acquired some views about what makes a great numbers guy.

I prefer working with someone fundamentally conservative. Bullish chief finance officers are dangerous. The leader of a business needs to be an optimist, and sales-oriented. But every business needs at least one person at the top alongside them to worry about the downside. I insist that the senior finance person is a qualified accountant. Whether they are a certified public accountant or a chartered accountant, they will have been taught how vital prudence is when preparing accounts, budgets and so forth. I am always astonished at how huge US corporations, like Enron and leading investment banks, can hire go-go MBAs as their CFOs. No wonder they got into trouble.