Harry Potter manners

Almost as bad as shouting “Fire!” in a crowded theatre would be yelling out the identity of the murderer as the curtain rises on the second half of The Mousetrap. Yet it doesn’t take more than two minutes with Mr Google’s well known search-engine to find the answer. After a 64-year continuous run, the play’s chief attraction now is the curious one of having run longer than any other. It is an achievement that Harry Potter

and the Cursed Child could no doubt emulate. All 175,000 tickets for its planned run have already been sold, so giving away the plot might do no commercial harm. It’s just one of those things one does not do, like getting jam on the butter knife, standing on the left side of the escalator or clapping between movements. Courtesy applies to worlds of fantasy too.