From the end of the Second World War, Western capitals were dominated by fear of what intelligence chiefs called a 'Nuclear Pearl Harbor'. Atomic bombs, new biological and chemical weapons, together with ballistic rockets such as the V-2, against which there was no defence, combined to create a new atmosphere of menace. Devastating surprise attack was the constant fear in the uneasy peace that stretched ahead. London and Washington responded by demanding better warning systems and so followed the prodigious growth of a Western intelligence community of unparalleled size and power. Strategic weaponry was now the No.1 target for British and American intelligence services.

Meanwhile, under the precarious ceiling of nuclear deterrence, London, Washington, Moscow and Peking all sought new ways to play out the Cold War struggle. They turned, once again, to the secret services, but now to further develop the new forms of clandestine warfare that had mushroomed during the Second World War, including underground armies, radio warfare, economic destabilisation and cultural subversion. The era of Cold War Fighting had begun.

Special operations or covert action by secret services transformed the Cold War, from an old-fashioned conflict between states, into a complex and bitter competition between societies. This was a secret struggle fought at every level. By the 1950s, the secret services of both the West and the Soviet Bloc were covertly funding political parties, trade unions, student groups, writers, painters and even ballet troupes in the competition between two different systems. This, in turn, required the secret services to interfere in every corner of domestic life, in a manner hitherto unknown either in peace and war. These underground activities, which did not always remain hidden, confronted post war premiers with a roller coaster ride.

Bitter arguments over provocative Cold War Fighting developed in Whitehall and Washington and by 1952 the CIA was accusing SIS of 'fouling up their operations' in the Eastern Bloc. Some officials in London had come to regard the Americans as bent on provoking World War III. Documents sent to Churchill, and revealed for the first time in this book, show that British intelligence chiefs believed that the American military had set a target date for war in 1952 which Britain would be obliterated. This remarkable study shows, for the first time, that the major British aim in the Cold War was not to only contain the Soviet Union, but to contain the danger of a hot war provoked by over-hasty American action, perhaps by the US Air Force.

Yet close Western intelligence collaboration was necessary to watch the Eastern Bloc, which was a tough target. This book draws hundreds of the latest files declassified by government relating to post-war signals intelligence by GCHQ and by co-operating signals units of the Royal Navy, the British Army and the Royal Air Force. It discusses the rapid development of post-war signals intelligence into the premier source of Cold War intelligence, discussing key overseas listening post at locations such as Germany, Cyprus, Ceylon and Hong Kong. It contains new details about post-war airborne ELINT co-operation with the USAF and the first submarine based SIGINT operations off Murmansk. It details the reaction of Winston Churchill in his second administration (1951-5) to a Soviet campaign of bugging of Western buildings and headquarters. It also contains remarkable details of efforts to counter a hitherto unknown Soviet signals intelligence site in North London at Whetstone, targeted on British defence exercises.

What role did Western secret service play in the Cold War? For British Prime Ministers, secret service helped to sustain post-imperial influence and to protect interests with minimum costs and visibility. The fancy footwork of skilful retreat from a global empire required constant assistance from the hidden hand of secret service. Britain's intelligence contribution to the Western 'pool' offset military decline and allowed influence over friends. Britain retained her status as a secret service world power for much longer than anyone has suspected. For Americans Presidents, secret power also helped to square difficult circles. Secret service helped address a world in which Washington proclaimed that all states should be free, but in which a disconcerting number of free states chose non-alignment and criticised the leadership of the United States. Above all, American secret service allowed the extension of the power of the President over American foreign policy.