The British prime minister is universally acknowledged to be the most powerful single individual in the British system of government, but very little is known about what goes on behind the closed door at #10 Downing Street. As Anthony King points out, there are few articles-let alone books-on the prime ministership available to students of British politics either in the UK or the US. As the preface to the American edition states, while the British prime minister and the American president do resemble each other in some ways, it is important right at the start to recognize the profound differences between them.