Historian of Stalinism and robust right-wing polemicist

Among western historians of the Soviet Union, Robert Conquest, who has died aged 98, had a unique place. In 1989-1990 his account of the terror of the 1930s was translated and published in a Soviet journal. At the same time, a half-dozen other Soviet journals were publishing translated material from his other books.

He was not the first to describe the extent and workings of the Stalin tyranny, but he did so in fine detail, becoming, for a broad Russian readership, the man who told the truth about Stalin’s murderous tyranny.

The Great Terror (1968) undermined the official Soviet story of conspiracy and treason. Conquest demonstrated that the show trials of old Bolsheviks were the product of faked evidence, torture, blackmail, threats and deceit. He explained in carefully documented detail the mechanism of the arrests, interrogations – the "conveyor" of continuous interrogation, denial of food and sleep and extreme physical abuse – and the mechanics of the trials.

Absolute power

He was perhaps less persuasive explaining why the terror had been created, falling back on the motivation of Josef Stalin, his drive for absolute power. Critics have continued to challenge his view that in the last analysis the purge depended upon the personal and political drives of Stalin alone.

The Great Terror remains Conquest's major work. Further studies deepened his account of the terror. Kolyma: The Arctic Death Camps (1978) and his history of the collectivisation of agriculture, The Harvest of Sorrow (1986), were forensically argued investigations of aspects of Soviet life that had been denied or ignored by many western commentators.

Conquest was himself a former communist, then a supporter of the British Labour Party and finally a speechwriter for Margaret Thatcher. He became a welcome figure in the richly endowed circuit of conservative thinktanks in the US. From 1981 his academic perch was as at the Hoover Institution at Stanford University, California. He was a vigorous and sometimes vicious polemicist, seldom happier than when challenging western admirers of the Soviet Union, such as EH Carr and Eric Hobsbawm.

Robert Conquest was born in Malvern, Worcestershire, to Rosamund (née Acworth) and Robert Sr, a well-to-do Virginian. His parents lived in San Remo on the Italian riviera during his childhood, and Italian and French were spoken at home.

Educated at Winchester, he won an exhibition to Magdalen College, Oxford, later completing a doctorate in Soviet history. He had joined the Communist Party at Oxford but broke with it when it denounced the war in 1939 as imperialist and capitalist.

Wartime work

During the conflict he was posted as a liaison officer Bulgarian forces serving with the Soviet third Ukrainian front. After demobilisation he joined the foreign office, and was in Sofia when the communists took over in 1946.

Conquest became a research fellow at the London School of Economics in 1956; several other university posts in the US followed. The publication of his first volume of verse, Poems (1955), was followed by New Lines (1956), an influential anthology of verse by younger poets. New Lines brought him into contact with Kingsley Amis and Philip Larkin, who remained close friends for decades.

Conquest shared with his two literary friends an enthusiasm for light verse and a weakness for would-be shocking expressions of right-wing politics. Often his limericks were bawdy but sometimes they reflected his ideological views: “There was a great Marxist named Lenin / Who did two or three million men in. / That’s a lot to have done in / But where he did one in / That grand Marxist Stalin did ten in.”

Conquest was invited to talk about Russian foreign policy with Margaret Thatcher while she was in opposition, and helped sharpen up her Iron Lady speeches. In 2005 he was given the US presidential medal of freedom by George W Bush.

Conquest’s first three marriages – to Joan Watkins, Tatiana Mihailova, and Caroleen Macfarlane – ended in divorce. He is survived by his fourth wife, Elizabeth Neece, whom he married in 1979, and by the two sons of his first marriage.