David Cairns – musicologist, conductor, critic, and an unsurpassed biographer of Berlioz – noses his new biography of Mozart out into the roaring traffic prevailing in this 250th anniversary of the brat’s birth (27 January is the day) with becoming hesitancy: ‘Another book on Mozart and his operas may not be needed. I can only say that I needed to write it.’ It is the fruit of sixty years’ listening, watching and writing, and you feel a certain fear on opening it – the same fear as when the opera bore approaches in the Coliseum bar with the implacable intention of telling you precisely what to think.

Imagine my relief when, with rare exceptions, Cairns turned out to be less the obsessive than the bar’s Ancient Mariner. Operaphiles believe that they alone hold the key to the works they love and know so well: I treasure the memory of one of my colleagues flouncing out of Calixto