Those who remember reading 'Harry Potter and the Philosopher's Stone' when it was first published may well be aghast to discover that was a whopping 20 years ago – yes, the global phenomenon that is the Boy Who Lived is officially two decades old. The British Library are pulling out all the stops on this celebratory exhibition, modelling each room around a Hogwarts subject. Just don't fall asleep in the Divination room.
