Tony Blair’s decision to mix business with statecraft by joining JPMorgan Chase as a part-time adviser while serving as an international envoy to the Middle East marks an unwelcome blurring of the line between public and private roles.

Jamie Dimon, JPMorgan’s chairman, said it was important to both men “to try to make the world a better place and have a bit of fun doing it”. That is all very well, although Mr Dimon was being characteristically blunt. The question is whether peace-making and money-making sit well together.