Australian Dictionary of Biography

Rosa Sibella Macarthur Onslow (1871-1943), charity and church worker, was born on 4 June 1871 at Camden Park, Menangle, New South Wales, third of eight children and only surviving daughter of Captain Arthur Alexander Walton Onslow, R.N., and his wife Elizabeth, daughter of James Macarthur. Brought up at Camden Park, she was educated by her mother and later by an elderly German tutor. She enjoyed singing, dancing and acting: musical evenings and a choir were organized at Camden Park by Miss Emmeline Woolley and Miss Ethel Pedley.

After her father died in 1882, Sibella assumed considerable responsibility for her brothers, as her mother was the proprietor and very much in control of Camden Park with some 20,000 acres (8094 ha). In August 1899 Camden Park Estate Pty Ltd was registered as a private company with Elizabeth managing director and her six surviving children directors. The right for Elizabeth and her issue to use the surname Macarthur Onslow had been granted by royal licence on 12 March 1892.

While her brothers were being educated in England, Sibella was overseas in 1887-90, 1892-94 and 1902, when she helped to form the Ladies' Empire Club in London. At home, when her brother George founded the People's Reform League of New South Wales, to raise the standard of morality in public life, she joined him and spoke to women to awaken them to the importance of their vote. Her mother died in London in 1911, bequeathing Camden Park, the surrounding 963 acres (390 ha) and £20,000 for its upkeep to Sibella for life. This was a great compliment to her capabilities over those of the heir, her brother James William.

Saddened by the deaths of her brother William and of her cousin A. J. Onslow Thompson during World War I, Sibella, an Anglican, turned to the Church. She took a generous and discerning interest in the welfare of the local parish, belonged to the Mothers' Union and the Ladies' Home Mission Union, taught once a week at the Camden school and during the 1919 influenza epidemic fearlessly organized relief hospitals. She was a member of the Australian Board of Missions and chaired its Sydney Diocesan Women's Auxiliary.

Meanwhile in 1914 Miss Onslow had joined the central executive of the New South Wales division of the British Red Cross Society and was secretary (president from 1930) of the Camden branch. She was a founder and deputy president in 1924-43 of the Victoria League in New South Wales; president of the Queen's Club, Sydney, in 1920 and 1922-25; and active in the Bush Book Club of New South Wales and the National Council of Women of New South Wales, representing the latter at the 1927 biennial conference of the International Council of Women at Geneva. In 1930 she was appointed C.B.E.

Camden Park was her life: there Sibella entertained such distinguished visitors as the Duke and Duchess of York in 1927. In 1914 she published Some Early Records of the Macarthurs of Camden, which her mother had begun. She was a caring and erudite gardener and loved animals; as well as her dogs she kept tame Australian birds and animals. Tall and good-looking, Sibella had charm and a great presence, but was in no way intimidating. Ill health bothered her at times and her normally reliable temperament could become very excitable. She once admonished a gentleman caller anxious to sketch the house, and much to her chagrin Camden Park was a notable omission from Hardy Wilson's Old Colonial Architecture.

In 1931, aware of her mother's testamentary wishes that Camden Park remain in the family in perpetuity, she exchanged houses with her brother James, moving to nearby Gilbulla. She died there on 16 July 1943 and was buried in the family cemetery at Camden Park; a memorial service was held at St Andrew's Cathedral, Sydney. Her estate was valued for probate at £80,326, and was left mainly to her nephews and niece.