Dame Elisabeth Murdoch: Philanthropist and key figure in the rise of her son Rupert

A pillar of Melbourne society for most of the 20th century, Elisabeth Murdoch was made a Dame of the British Empire in 1963 for her wide-ranging charitable and voluntary work, in particular for establishing an institute for research into children's health problems. Yet she was best known as the formidable mother of Rupert Murdoch, the most successful media magnate of his generation, of whom she remained inordinately proud throughout his controversial career.

Following the death in 1953 of her husband, Sir Keith Murdoch, Elisabeth played an important role in the family trust that retained effective control of News Corporation, the holding company for the Murdoch empire, during its years of remorseless growth. She retained a share in the business even after Rupert had bought out the interest of his three sisters. He was always reluctant to take critical decisions affecting the family's role in the group without first gaining her approval.

Born in 1909, Elisabeth was the daughter of Rupert Greene, a high-spirited Melbourne gambler. She was sent to a good school and grew up a bright girl, slightly built, adept at sports, especially swimming. In 1927 she came out as a debutante, and her picture appeared prominently in an issue of Table Talk, a gossipy magazine published by the Melbourne Herald.

The editor of the Herald was Keith Murdoch, a 43-year-old who had made his reputation reporting the horrors of Gallipoli. He was attracted by the photograph and arranged an invitation to a charity ball he knew Miss Greene would attend. The following week he invited her to drive with him to Sorrento, a stylish beach resort.

In the 1920s it was still seen as risky to entrust vulnerable young women to the mercies of dashing blades in cars, and Elisabeth's parents had doubts about letting their daughter go motoring with a man more than twice her age. They agreed because of Murdoch's flawless credentials but insisted that a chaperone – a titled chaperone, at that – should go along too.

Other outings followed, and the couple were married, with Dame Nellie Melba among the guests at the reception. After marriage, they moved between Melbourne and Cruden Farm, a rambling place with 90 acres of land. In 1929 Elisabeth had her first child, Helen. Rupert, second of four children and the only boy, was born in 1931.

Keith had been made managing director of the Herald and Weekly Times Group, and rose to be chairman. In 1933 he was knighted and began acquiring stakes in newspaper groups in Adelaide and Brisbane. Elisabeth never considered a career but she began voluntary work, joining the management committee of Melbourne's Royal Children's Hospital in 1933, later becoming president.

The couple were grooming Rupert to be Sir Keith's heir, enrolling him at Geelong Grammar, Australia's elite boarding school, and toughening him up by making him sleep in a tree house at Cruden during the summer holidays. In 1949 he was sent to Oxford University but his fondness for drinking and gambling and his reluctance to apply himself made Sir Keith think of pulling him out. Elisabeth dissuaded him. She went to Oxford and gave her son a talking-to which shook him to his bones, as he confessed to Thomas Kiernan, one of his biographers.

Rupert was in his last year at Oxford when his father died in 1952. Elisabeth was a trustee of Sir Keith's will, in which he bequeathed his holdings to Rupert so long as he was thought fit to run them. The other trustee, a newspaper executive, told Elisabeth – who had played no role in the business – that the Brisbane and Adelaide papers should be sold for death duties, depriving her son of his inheritance. She insisted on keeping the Adelaide News.

Before returning to run the Adelaide News, Rupert spent several months as a sub-editor on the Daily Express, and enjoyed it so much he wanted to stay. His mother ordered him back, and gave him another lecture on living up to expectations. During his absence she had been approached by the owner of the Adelaide Advertiser with a high cash offer for the News. She refused. Had she weakened, Rupert would have been deprived of the foundation of his present-day global empire.

Although she never played an active role in running the business, she was always an influential figure in the background. In 1968, when Rupert was negotiating to acquire his first British paper, the News of the World, she came to London to lobby on his behalf with the proprietor Sir William Carr and his wife, whom she knew socially. She feared her son's brash manner might alienate those whose support he needed, and calculated correctly that her patent respectability would go some way towards softening his image.

Not that she approved of scandal sheets like the News of the World or the raucous tabloids Rupert had accumulated in Sydney and elsewhere. She accepted this was the way to create a powerful press group, but urged him to broaden the portfolio to include papers of the kind she and her friends would be proud to have in the house.

She made the point forcibly on her return in 1963 from her investiture at Buckingham Palace. Kiernan quotes her as telling her son that he was tarnishing the family name with "all these horrid papers you're putting out" and urged him to "publish something decent for a change". The sally struck home and the following year, to her delight, he launched The Australian as a serious national broadsheet. She was even more gratified when, in 1980, he added The Times and the Sunday Times to his British stable, at the other end of the market from The Sun and the News of the World.

"I've always believed that a mother's role, especially to a young adult, is one of kindliness, affection and courage; and perhaps one hopes to inspire them to rise to the best that is in themselves," she said. "And I did long to be able to help Rupert prove worthy of his father in the newspaper world."

Although her son often sought her advice he did not always take it. In 1983 he paid a substantial sum to serialise the supposed diaries of Adolf Hitler in the Sunday Times. Elisabeth, in London at the time, was sceptical about their authenticity, and told him he had been "sold a pup". He went ahead and published anyway, and they were duly shown to have been faked.

When he decided to become an American citizen, so as to be qualified to own television stations in the US, he was apprehensive about how his mother would react. According to William Shawcross, another of his biographers, he telephoned her from a hotel room in Arizona. When the difficult call was over, he told colleagues with relief: "She said it's OK as long as I can keep the Australian papers."

She took her son's domestic tribulations in her stride, too. When he announced in 1998 that he was divorcing Anna, the mother of three of his children, she conceded that it came as a shock; but she gave her blessing to his marriage to Wendi Deng. She never remarried, which meant that she spent more than half her life as a widow.

Her voluntary work took up more of her time. She became a trustee of the Victoria National Gallery, sponsoring an annual art prize, and helped found a state tapestry workshop. In 1962 she established the Murdoch Children's Research Institute, which has fostered research into children's health.

She was fiercely independent and unfailingly charming. In 1982, when I was researching my biography of her son, she invited me for lunch. She told me members of her family had tried to persuade her not to see me, since my book was unauthorised. "I told them it wouldn't be polite to cancel the invitation," she said. "And anyway I don't plan to be indiscreet." She was a model of discretion but still gave me invaluable insights into Rupert's childhood, coloured by her pride in his achievements. Then we went on a tour of her treasured garden: gardening was one of her enthusiasms.

Another visitor much taken with her was the actor Paul Eddington. In his autobiography, So Far So Good, he expressed a common view: "It was hard to believe that such an obviously wonderful woman could have bred the monster so many believed him [Rupert] to be." Naturally, she did not accept such assessments of her son's accomplishments and, over her long and fulfilling life, developed the mental toughness to brush them aside.

Elisabeth Joy Greene, philanthropist: born Melbourne 8 February 1909; CBE 1961, DBE 1963; married 1928 Keith Murdoch (died 1952; three daughters, one son); died 4 December 2012.