I am due to meet Jeffrey Sachs in his choice of restaurant, La Porte des Indes, on a quiet central London backstreet. It’s an unremarkable entrance, but once inside the space opens up to give the impression of colonial India, complete with wicker furniture and palm trees growing from the floor below.

The Columbia University economics professor, and director of the Earth Institute, is already there, in conversation with his assistant, Margot. I realise that Sachs is no longer just an eminent academic, he is a brand, and travels the world with an assistant in tow, spreading his economic gospel. I introduce myself, and Margot goes off to have some lunch at another table while ensuring that we don’t overrun our tight schedule.