Sir Anthony Seldon is the acknowledged national authority on all matters to do with Number 10 and Prime Ministers. His first book on a Prime Minister, Churchill's Indian Summer (1981) was published forty years ago, and since then he has written or edited many books, including the definitive insider accounts of the last five Prime Ministers. He is the honorary historian at Number 10 Downing Street, chair of the National Archive Trust, and has interviewed virtually all those who have worked in Number 10 in the last 50 years. Marking the third centenary of the office of Prime Minister, The Impossible Office explains how and why it has endured longer than any other democratic political office. Sir Anthony Seldon, historian of Number 10 Downing Street, explores the lives and careers of our great Prime Ministers, discussing which have been most effective and why.