I’ve been trying to pinpoint the exact moment when it became impossible to take Mascagni’s Isabeau seriously. It wasn’t when the scenery jammed, leaving half the cast briefly trapped inside a revolving tower. These things happen, after all: you simply suppress thoughts of Spinal Tap and re-suspend disbelief. I don’t think it was the entry of a character called Ubaldo of Edinburgh either, though people were definitely starting to snigger.