From the Muppet Show to Kafka, Yiddish theatre to Vivaldi, pop music to Wagner – Barrie Kosky’s enthusiasms ricochet at a speed that leaves you dizzy as well as, in their rampant variety, a touch envious. This 58-year-old Australian theatre and opera director sees all art, all life, as one. His love of clowns, cabaret and musicals is as intense as his passion for theatre and grand opera. “Whether it touches the soul is all that matters,” he says, his loquacious personality expanding into a small side office at the Royal Opera House in London before a rehearsal. His new...