Watching BBC1’s Elizabeth Is Missing made one of the more puzzling decisions of recent decades seem more puzzling still. Entirely her call of course, but why on earth did Glenda Jackson give up acting (something she was better at than pretty much everybody else in the world) to become an unremarkable Labour MP (something that any number of people could surely have done just as well) for more than 20 years? Whatever her thinking, though, Jackson’s first TV role since 1992 was an overwhelmingly powerful and therefore quite sad reminder of what we’ve been missing.