The biggest annoyance in becoming pope, the former Benedict XVI says in a new book, was the cufflinks. He wasn’t used to wearing them, and “I thought that whoever invented them must be in the depths of purgatory.”

He said this laughing, for his latest book, called in English Last Testament, is an extended biographical interview with Peter Seewald, who first met him in 1992 and has published two other book-length interviews with him.

This book reveals a serious point about Benedict’s life, but first I want to say that I found the trivia about this holy old academic quite endearing.

Favourite opera? Don Giovanni. But the “pope emeritus”, who resigned the papacy in 2013, doesn’t like having music on when he is working: “Either music or writing,” he says. He wrote his books (including the three volumes on Jesus that he composed in his eight years as Pope Benedict XVI) in pencil, a habit he acquired from commenting on university students’ essays.

If he has to think something out, he lies on the sofa: “I always need a sofa.” He likes seven or eight hours sleep a night: “That is non-negotiable,” even if he ran up a deficit on being elected pope. He was never sporty and resented in his youth the Nazi insistence on schoolboys having to pass in sport to finish school. But he has walked every day and thought nothing of a 20-mile walk to visit the grave of his favourite comedian (Karl Valentin).