By background I'm both a Quaker and a Yorkshireman, which I like to call double jeopardy.

I hate gold. It does not pay a dividend, it has no value, and you can't work out what it should or shouldn't be worth," he said. "It is the last refuge of the desperate.

The investment business has taught me – increasingly as the years have passed – that people, especially investors (and, I believe, Americans), prefer good news and wishful thinking to bad news; and that there are always vested interests to offer facile, optimistic alternatives to the bad news.

Remember that history always repeats itself. Every great bubble in history has broken. There are no exceptions.

Think how weird profit margins are: We've got high unemployment and financial crises - and world record profit margins. People think the American market is very cheap. We don't. The market quite incorrectly gives full credit to today's earnings.

Profit margins are probably the most mean-reverting series in finance, and if profit margins do not mean-revert, then something has gone badly wrong with capitalism. If high profits do not attract competition, there is something wrong with the system and it is not functioning properly.

I find the parallels between how some investors refuse to recognise the trends and our reaction to some of our environmental challenges very powerful. There is an unwillingness to process unpleasant data.