The postwar era as seen by a master of counterespionage--with an insight into his professional downfall.   Guy Liddell was the director of MI5's counterespionage B Division throughout the Second World War, during which he wrote a confidential personal diary, detailing virtually every important event with intelligence significance. Those recently declassified diaries, which were edited by Nigel West, have now been followed by a postwar series which covers the period from the German surrender until Liddell's sudden resignation in May 1953.   These eight years contain many disturbing secrets, such as the cache of incriminating Nazi documents which was supposed to be destroyed by the SS. When these were recovered intact, the British government went to considerable lengths to keep them from being disclosed, for they provided proof of the Duke of Windsor's contact, through a Portuguese intermediary, with the enemy during the crucial period in 1940 when the ex-king declared himself ready to fly back from the Bahamas and be restored to the throne. One of Liddell's first tasks, at the request of Buckingham Palace, was to retrieve and suppress the damaging material.   Liddell's diaries were never intended for publication--and are filled with indiscretions that shed new light on MI5 investigations he supervised after his promotion to deputy director general. In addition to such behind-the-scenes stories, this book includes details about the end of Liddell's career and the mistakes that led to it. Despite Liddell's manifest failings, and his reluctance to believe in the disloyalty of men he regarded as friends, he was probably the single most influential British intelligence officer of his era.   "[Nigel West's] information is often so precise that many people believe he is the unofficial historian of the secret services." --The Sunday Times