Two years ago, investment banker Jeffrey Flug received an unusual approach from a search firm. It was for a position as chief executive of Millennium Promise, the non-governmental organisation founded by economist Jeffrey Sachs and philanthropist Ray Chambers to fight global poverty.

Flug was surprised to be considered for the post. “I’d never spent a day in my life working with a non-profit,” he says. And when the search firm executive explained that this was a wonderful NGO, he admits his response was: “ ‘What’s an NGO?’ I knew what an IPO was and what an LBO was – but not an NGO.”