James Douglas, who has died aged 85, played an important role in the Conservative Research Department when the Tories' style of consensus politics had a strong appeal for the electorate, between Churchill's victory of 1951 and the defeat of Edward Heath in 1974.

During this time he made two major contributions to the modernisation of the party's practical operations.

He devised the rules introduced in 1965 to provide for the election of the party leader, though an egregious MP, Humphry Berkeley, stole the public credit. He also vigorously promoted the use of opinion polls - at which his predecessors had looked askance - though he deplored the mumbo-jumbo that was so often attached to them.

It was thus that the party discovered a previously neglected element of the electorate, the C2s, whom Mrs Thatcher later courted so successfully with the sale of council houses.

From the moment he joined the department's offices, overlooking St James's Park, in 1951 after many of its post-war luminaries had left to find parliamentary seats, Douglas played the part of a slightly unworldly professor to perfection, and widespread delight. At the same time he established himself at the forefront of discussions of policy and strategy where the most important work was done.

Although never zealous in his Tory faith, he was admirably forthright in his advice; a Douglas memorandum was always awaited with keen anticipation by colleagues and some trepidation by ministers. One draft of the 1966 election manifesto drew his caustic comment: "It could equally well have been put out by the Labour Party."

As the election of February 1974 drew near on Heath's ill-chosen issue of "Who governs Britain ?", Douglas , by then head of the department, argued passionately that the party needed a clear bold message. Above all, he argued, it must replace "fussy little defences of the latest stage of the Heath government's counter-inflation policy".

"If we outlive this day and come safe home," he asked, "will we indeed rise up and stand atiptoe at the name Stage Three?" It was his misfortune that, after years of enlivening internal Tory debate, he lost his post in the reorganisation that followed the first 1974 election defeat. However, Douglas gave way very graciously to his successor, Chris Patten, for whom he entertained a very high regard.

James Alexandre Thomas Douglas was born on July 22 1919 at Simla, where his father commanded a regiment of the Indian Army. He was brought up in Paris before being educated by the Jesuits at Beaumont College in Berkshire .

After reading PPE at New College , Oxford , he took up a post at the Board of Trade where he had responsibility for clothes rationing. For years afterwards he embodied the war-time lack of choice, always wearing striped trousers and a black jacket. Thus attired, he cut an incongruous figure on his Lambretta motor scooter, weaving dangerously through the traffic with his mind on political strategy.

Yet he was as conscious as any future Thatcherite of the need for business to give value for money. Douglas became a founder member of the Consumers' Association, where he helped to launch the magazine Which? In 1963, he was appointed OBE.

Throughout his career in the research department, Douglas remained largely unknown, and took little interest in life as it was led in the constituencies. His heart was not gladdened by Thatcherism. One former Cabinet minister was heard to muse, around 1992, "I wonder whether any of the five surviving CRD Directors voted Conservative at the last election?"

After leaving the research department in 1977, Douglas held senior academic posts at Yale, Columbia and the Northwestern University before taking up, in 1986, a Woodrow Wilson Fellowship at Princeton, though with his sharp approach to politics he could have had little sympathy with that President's vague principles for a new world order.

James Douglas retired to Hampstead, where he died on September 20. He is survived by his widow, the former Mary Tew, professor of anthropology at University College , London , two sons and a daughter.

He also leaves a fine example to politicians as a whole - generally a self-satisfied breed; he never took himself too seriously and liked to mock gently their pretensions.