The film is remarkable for a number of reasons. For one, it's amazing that such a compelling drama was produced from such a small event: the decision by the Queen (Helen Mirren) to publicly acknowledge the death of Diana and to lower the flag over Buckingham Palace to half mast. As he did with "Frost/Nixon" (2008), writer Peter Morgan has unearthed a truly interesting story about power from a relatively trivial setting.
Second, the film turns out to be a fascinating study of the power of public opinion, which can even constrain unelected officials. Queen Elizabeth II is depicted as living an insulated life, but the sounds of the outside world keep disturbing her. When newspaper editors demand that she make some public display of mourning in the wake of Diana's death, she refuses to bow to them. Indeed, she views it as her duty not to bow. She sees herself as the embodiment of British tradition, and the British simply soldier on in the face of adversity.
Her adherence to this duty, however, ends up threatening her rule. She is visibly shaken by news that a majority of her citizens feel she has hurt the monarchy, and a quarter of them favor abolishing the crown altogether. Ultimately, she is saved by accepting the advice of Tony Blair (Michael Sheen), the new Prime Minister.
Blair is portrayed as everything she is not: young, middle class, modern, media savvy. But most importantly, as a politician, Blair understands the importance of public opinion. His handling of the Queen is an interesting case study in leadership. He convinces her to do what she does not want to do but is nonetheless in her best interests. She preserves the traditions of her office by sacrificing some of them.
If you're teaching about leadership, tradition, or public opinion, or you just want to see a good film, I highly recommend this.