Had she wanted to, Kate Mortimer could have risen to the top of any number of professions. As it was, she moved easily between the public and private sectors, between the World Bank in Washington and private banking in the City of London, between the British Government’s Know-How Fund for Eastern Europe and several heavyweight non-executive directorships.

A more ambitious person might have had a less zig-zag career, but hers was more connected than it seemed. A strong concern for international development was common to many of her jobs, and she brought to all of them a clear-minded commitment to principles. As an adviser and regulator, she promoted ethical standards in private industry. As a practitioner with experience in the world of business, she helped to make things happen in her developmental work.

Katharine Mary Hope Mortimer was the youngest of the four children of Robert Cecil Mortimer, Bishop of Exeter, and his wife, Mary Hope Walker. They were a clever family and Kate was one of the cleverest. She was also highly attractive, both in looks and in personality. At Oxford, where she took a first in politics, philosophy and economics before going on to do a BPhil in economics, she shared a house with three other formidably clever and good-looking women, all of whom have become academics: Caroline Elam (now an art historian), Emma Rothschild (an historian and economist) and Marina Warner (the novelist and historian). Kate, however, was the only one to play cricket for the university, earning herself a half-blue.

Home for Mortimer was the bishop’s palace in Exeter, where her father composed his sermons and helped to revise the canon law of the Church of England; he was a former regius professor of moral and pastoral theology at Oxford. Her mother, no intellectual slouch herself, meanwhile dispensed cheese sandwiches through the kitchen window to a succession of mendicants. Edward, the younger of her two brothers, would also have a sparkling intellectual career, as (among other roles) a foreign specialist and leader writer for The Times (1973-87), the main foreign affairs commentator of the Financial Times (1987-98) and (since 1998) head of the UN speechwriting unit.

Emerging from this gene pool, Kate might have been intimidating. Far from it. Her sharpness of mind was never in doubt — she would make short work of the Times crossword — but she had no interest in academic pretentiousness and could hardly be called intellectual, certainly not highbrow. She read voraciously, but mostly novels, especially thrillers. Nor was she remotely puritan. She enjoyed herself. Her stockings were more fishnet than blue.

After Oxford, a job at the World Bank involving water development took her to West Africa, South-East Asia and East Pakistan during its cyclone-precipitated transformation into Bangladesh. In 1972 she returned to Britain to work for the Central Policy Review Staff, set up by Edward Heath under Victor Rothschild, the Cambridge scientist who had worked for MI5 during the war and later became head of research at Shell. The Think-Tank, as it was known, was supposed to produce intellectually original ideas. Working with Tessa Blackstone, now a Labour peer, Mortimer proposed a set of reforms for the Foreign and Commonwealth Office that caused diplomatic hissy fits in British embassies all over the world. Today their proposals seem less than iconoclastic.

Next came the City, where she worked for N. M. Rothschild for six years, before being seconded to the Securities and Investments Board as director of policy during a formative period for financial regulation.

Her Oxford friend Sebastian Walker then asked her to become chief executive of his hugely successful children’s book company. The episode ended with a row that left Mortimer feeling bruised, though the company continued to prosper.

The collapse of communism in Europe in 1989 brought new opportunities. William Waldegrave, another friend from Oxford and the Think-Tank, was now a minister at the Foreign Office and appointed Mortimer to be one of those using Britain’s Know-How Funds to introduce the arts of capitalism to the new economies emerging in Eastern Europe and the Soviet Union. Thus she returned to her early development work, this time with the benefit of practical experience in business and finance. In due course she joined the boards of several companies, among them National Bus, Crown Agents Asset Management, British Nuclear Fuels and Pennon Group, the owner of South West Water. She also served on the Competition (formerly the Monopolies and Mergers) Commission, the Centre for Economic Policy Research and at Imperial College.

Though work was important to Mortimer, it was always done with no apparent effort, and certainly no fuss. Her first marriage broke up, but her second, in 1990 to Robert Dean, was very happy, and she was devoted to her son and stepchildren. She seldom spoke about her religious beliefs, but all that she did suggested that they mattered greatly to her. For all her extrovert warmth and sense of fun, she was as unostentatious about her faith as about her intelligence.

Kate Mortimer, economic consultant, was born on May 28, 1946. She died of cancer on July 15, 2008, aged 62