The second of four children, Linda Fisher was born on November 17 1942 in Binfield, Berkshire, to Antony Fisher and his first wife Eve, née Naylor, and brought up at Newplace, a large house in Framfield, Sussex, with 440 acres of farmland, that her father bought after the war and where he founded Buxted Chickens, now part of Allied Foods.

Linda and her siblings enjoyed a carefree outdoor upbringing on the farm. One of the few rules their father enforced was that they should attend the parish church at Framfield with their mother, and the Church of Christ Scientist at Haywards Heath with him on alternate Sundays.

As a result Linda had a fairly cursory formal education, with brief attendance at St George’s, Ascot and St Clare’s, Oxford. She was presented at court as a debutante in 1962 after a year in the US where she did short courses in economics and governance.

She would later take A-levels at a London “crammer”, but her father was her main educator: “He never disciplined us or made a conscious effort to teach or train or guide us. If he did it was by example because we all wanted to please him.”

Antony Fisher’s informal lessons in political economy had a profound effect on his children, though not on his wife, a Conservative in a more traditional mould. Her son Mark recalled that when his mother chaired political meetings in the village hall, he, his father and siblings would sit in the audience “shouting, ‘Boo’.”

Linda’s parents’ marriage would break down in the late 1960s, after which they both remarried.

Linda’s first job was as a researcher in the Economist Intelligence Unit and in 1963 she married Francis Whetstone, a Lloyds underwriter. While bringing up their three daughters, she took a degree in Economics by correspondence at the University of London.

In 1969 the Whetstones bought a dairy farm in East Sussex which Linda managed, milking all the cows herself once a fortnight. She later changed to rearing heifers, then in the 1990s converted the farm buildings into small workshops.

She and her husband often accompanied her father to MPS meetings and, beginning with a paper on milk marketing in 1970, Linda began writing reports on agricultural policy for the IEA and the Adam Smith Institute which would eventually prove instrumental in dismantling market controls in agriculture.