Why outing Dumbledore was a wizard wheeze

One summer afternoon a friend confided in me that she was five months' pregnant. "Of course you are," I said, staring at the sizeable bump which, until that second, I simply hadn't seen. I felt much the same when Albus Dumbledore, headmaster of Hogwarts School and all-round hero, was brought out of the closet, in Carnegie Hall, by his creator, J K Rowling.