The matter-of-fact approach of this British diplomat offers fewer revelations here than in his memoir of troubleshooting in The Middle East in Revolution (1971), but this account of life and work in China and the U.S.S.R. is equally engaging. Pragmatically seeking to sustain good trade relations, England sent him to negotiate diplomatic relations, and during 1953-55 he explored cities and shops, sparred in the middle of the night with Chou En-lai, hung around the Geneva Conference -- he says reports of his influence there are exaggerated -- and took a detached view of the Taiwan crises, into which the U.S. kept dragging the British. As far as it goes, his ""power game"" view of the Cultural Revolution as a matter of Mao shaking up the bureaucracy ""from outside"" makes sense. Presently Trevelyan learned Russian and arrived in Moscow at the time of the test ban treaty, staying till 1965. The Soviets, he says, ""regarded us as the only people able to exert some influence on the Americans."" The sections on trade and culture are more illuminating than those on Laos and Vietnam; what is bound to interest readers is his side glance at the intelligence game between the British and the Russians: ""The principle underlying the battle was reciprocity. . . . The rules of the game were well defined and understood by both sides."" He also adds to our stock of the Radio Armenia jokes popular there: ""What is the name of Khrushchev's hairstyle? Harvest, 1963."" A marginal but rewarding mixture of the caustic and good-humored.