You would be forgiven for thinking the great Japanese anime master Hayao Miyazaki, 82, has made his last film. After the realism of 2013’s The Wind Rises, which scanned the skies of pre-second-world-war Japan for the industrial-era upcurrents of inspiration, he makes a return to full-blown fantasy in his latest, The Boy and the Heron. It is hard not to take the magus figure of the film’s Great-Uncle, looking for a successor to steward this realm of man-eating parakeets and flying dim sum, as Miyazaki’s Prospero moment; his breaking of his creative staff. Then you remember: this is the fourth time he has announced his retirement.