Marking the third centenary of the office of Prime Minister, this book tells its extraordinary story, explaining how and why it has endured longer than any other democratic political office in world history.Sir Anthony Seldon, historian of Number 10 Downing Street, explores the lives and careers, loves and scandals, successes and failures, of all our great Prime Ministers.From Robert Walpole and William Pitt the Younger, to Clement Attlee and Margaret Thatcher, Seldon discusses which of our Prime Ministers have been most effective and why.He reveals the changing relationship between the Monarchy and the office of the Prime Minister in intimate detail, describing how the increasing power of the Prime Minister in becoming leader of Britain coincided with the steadily falling influence of the Monarchy.This book celebrates the humanity and frailty, work and achievement, of these 55 remarkable individuals, who averted revolution and civil war, leading the country through times of peace, crisis and war.