With some notable exceptions, the most eminent of which is Beethoven’s Fidelio, the theme of maintaining marital loyalty, whilst morally so commendable, is theatrically utterly boring. Its opposite, instead, always affords interesting theatrical shambles which can range from the vaudeville to tragedy and everything in between. If Händel’s Rodelinda, a story about staunch marital loyalty, theatrically is not only tolerable but works rather well is because deep down it...