Theirs was a unique relationship. It was based on interlinked national histories and partially shared nationality, similarities in class and education, a common belief in the superiority of Anglo-Saxon institutions and the twin enemies of Nazi Germany and Imperial Japan. It developed into almost daily communication, either by telegram, telephone, personal meetings or through intermediaries.At the heart of this special relationship, hidden by layers of secrecy, was an extraordinary and far-reaching sharing of intelligence and fascination for clandestine operations. There the two leaders played a crucial personal role. This was the most sensitive touchstone of their mutual trust, and as David Stafford's masterly study demonstrates, a responsive barometer of suspicion and discord.