In a deeply undignified start to my interview with one of the world’s most famous spiritual leaders, I am pressing my face against the glass of the Ismaili Centre in South Kensington, gesticulating wildly as I try to catch the eye of the dark-suited security man. It seems to me he is, perhaps reasonably, deliberately ignoring the madwoman outside.

As I’ve already tried pushing the locked door, I eventually stand on the street corner and rummage inelegantly in my bag to find my phone. After a long wait, I manage to get hold of a friend who works for His Highness the Aga Khan, who lets me in.