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.

The CFO must be able to assemble and analyse financial statements themselves: I do not want a quick-talking professional who has risen so far that they do not understand the business's accounting systems. But they must also be able to see the whole picture and not get so immersed in detail that they overlook major issues – a surprisingly common failing.