John Osborne Plays 1: Look Back in Anger, Epitaph for Geroge Dillon, The World of Paul Slickey and Déjàvu

According to Wiki and academic reviews, Look Back in Anger changed British theater. That's a statement I can't qualify. The only think I can say is that Look Back in Anger is probably the first literary work about the British lumpen, a class that would become the majority in the last 50 years. Irvine Welsh and Hooligan, just to mention two examples, cannot be explained without John Osborne's work.