“In the straight theatre, the interval norm has long been 15 minutes, giving those quick off the mark just enough time to swallow a warm, over-priced gin and tonic before nipping to the loo. (My own preference is a brisk walk round the block.) Recently, the National Theatre has extended the standard to 20 minutes, and, given the number of slower, older people in today’s audiences, perhaps that is the optimum. However, the more puritanical breeds of theatre director don’t like reality impinging on their creations at all.”