The Show in Which Hopefully Nothing Happens is a child-centric theatrical masterpiece that feels like Pinter meeting pantomime for the Pixar audience. My two six-year-old co-critics were rapt from the moment they entered the Unicorn’s black box Clore Theatre and beamed and belly-laughed for the play’s duration. Veterans of quality children’s theatre, like The Gruffalo’s Child or We’re Going on A Bear Hunt, will be taken to a new level of audience engagement – even …