What’s Mozart’s Così fan tutte about? I doubt there’s a good answer to that question but one element of what it’s about is artifice. That appears to be Jan Philipp Gloger’s jumping off point for his Royal Opera House production filmed in 2016. I have pages of notes on how the setting changes and who is singing to whom about what at which point in the opera. It starts with the “cast”, in 18th century dress, taking a curtain call during the overture but it soon turns out to be a bit more complex. Dorabella, Fiordiligi, Ferrando and Guglielmo appear in the auditorium in smart modern dress as late comers taking their seats. Soon the boys are on stage in front of the curtain with Don Alphonso (for some reason dressed as a 17th century divine) while the girls hide in embarrassment behind their programmes.