Margaret Richardson, later known as Margaret Home Richardson, was born at Pencaitland, East Lothian, Scotland, on 19 March 1844, the daughter of Jane Law Home and her husband, John Richardson, an estate factor. In her youth she taught deprived children in the ragged schools of Edinburgh. She then trained as a nurse, working in hospitals under the Florence Nightingale system, and joined Josephine Butler's campaign for the repeal of the contagious diseases acts of 1864, 1866 and 1869.
In the 1870s Margaret Richardson emigrated to New Zealand, and on 29 November 1878 at Wellington she married William Sievwright, a solicitor from Lerwick, Shetland islands, who worked at the legal firm of Sievwright and Stout. William already had two daughters by his first marriage and the couple were to have one more. Margaret's father also joined their household. In 1883 the Sievwrights moved to Gisborne where William established his own practice. They bought a property on the hills overlooking the town and Poverty Bay in 1884. That year the Married Women's Property Act was passed and it is significant that the land title was registered in Margaret's name.
Margaret Sievwright was a tall, fine-looking woman with a retiring, sensitive nature that made her averse to involvement in public affairs. Her frail appearance belied the energy and tenacity with which she fought injustice and defended the rights of women and children. She was intelligent, well educated and articulate, and was encouraged by a liberal, supportive husband. After she had set up a small school on their property, she joined a benevolent society, which organised funds for community projects such as isolation wards for the local hospital, and a home for aged men.
Margaret Sievwright was appointed to the Waiapu Licensing Board and she organised the Gisborne branch of the New Zealand Women's Christian Temperance Union, the national organisation that was deeply involved with the suffrage movement in New Zealand. Along with other national leaders, Sievwright maintained strong connections with feminist movements overseas.
Between 1887 and 1892, despite continuous agitation, several women's franchise bills failed. In 1893 suffragists, headed by Kate Sheppard and Margaret Sievwright, took a petition of nearly 32,000 signatures to their leading pro-suffrage supporter, Sir John Hall. He presented the petition to the House of Representatives, and despite the obstruction of Premier Richard Seddon, the Electoral Bill finally became law. Women's political organisations undertook the task of educating women to use the vote effectively and influence legislation. In 1894 Sievwright convened the Gisborne Women's Political Association which she represented at the National Council of Women of New Zealand, formed by former suffragists in 1896 to co-ordinate the various women's groups. She was a vice president up to 1901, when she became president until her death in 1905. She established and was secretary of the Local Council of Waiapu Women in 1901 and was president from 1902 to 1904. The aims of this society were, first, to promote the further enfranchisement of women, and second, to bring individual women into touch with national and international women's movements. Sievwright's feminist vision was perhaps best expressed in a speech of 1900: 'The question is often asked, "What do women want?" We want men "to stand out of our sunshine"; that is all.'
Margaret Sievwright believed that broader emancipation could only be achieved through supporting political parties that promised to further the interests of women. She was an idealist aiming at total equality for all women. She wanted economic independence for married women, equal pay, and sex instruction and education for parenthood. She fought for the reform of the marriage and divorce laws, and maintained that prostitution would always exist as long as women lacked equal opportunity in employment. She objected to the stigma of the word 'illegitimate'. Sievwright worked for disarmament during the South African war (1899–1902), and condemned any project 'likely to involve Australasia in the participation of warfare'. For these beliefs she was castigated by the press.
By 1903 she realised the fire had gone out of the women's movement and complained that 'the apathy and cheerful indifference of the great majority is distinctly benumbing'. She prophesied rightly that it would take a long, hard struggle to rekindle it.
Margaret Sievwright died at Whataupoko, Poverty Bay, on 9 March 1905. Her husband, William, died in 1909. Their daughter Wilhelmina married Kate Sheppard's only child, Douglas Sheppard, in 1908. Margaret Sievwright's fellow workers recognised her life of self-sacrifice and devotion to the cause of women's advancement by erecting a monument to her in Peel Street, Gisborne, in 1906. An inscription reads, 'Ever a friend to the friendless, an uncompromising upholder of all that is merciful, temperate and just.'