Banks employ large teams of highly paid people to devise transactions mainly for the purpose of avoiding tax. These activities seem to be far more profitable than the humdrum business of managing payments and channelling savings towards investment. Why?

The answer shows the close link between tax avoidance and the speculation that has fuelled financial instability for 30 years. There were clearly other causes of the current crisis but the faults of the international tax system were a big contributory factor.

International tax co-ordination depends on treaties based on a model devised 80 years ago. To prevent double taxation, the treaties generally give governments the right to tax returns from an investment in the investor's country of residence. Business profits, meanwhile, are taxable in the “source” country where the activity takes place.