Margaret Jane Scott was born at Carnafane near the town of Cavan, County Cavan, Ireland, on 17 January 1869, the daughter of Anne Kenny and her husband, Henry Scott, a farmer. Little is known of Margaret's early life beyond the fact that the family arrived in Lyttelton, New Zealand, aboard the Halcione on 29 August 1880 and settled on land outside Christchurch.
After leaving school Margaret Scott trained as a tailoress in Christchurch. She became involved in the trade union movement which developed in response to revelations of poor working conditions in the clothing industry. From 1892 to 1897 Scott was the first female secretary of the Christchurch Tailoresses' and Pressers' Union, previously led by male officials. She was the union's representative to the Canterbury Trades and Labour Council and came to national prominence when she was elected a council vice president in June 1894. During 1894 she was active in the establishment of a co-operative society which employed 30 tailoresses put out of work by a factory closure.
In 1895, on the basis of her experience with women workers, Margaret Scott was appointed to manage the newly created Women's Branch of the Department of Labour in Wellington. The Women's Branch was established after much lobbying from groups such as the Women's Social and Political League, and through the columns of the women's paper Daybreak. They had asked for the creation of an employment bureau for women on the same basis as those established for men in 1891. Scott's was a popular appointment; she was the first of a number of female trade union officials (including Harriet Morison and Selina Hale) who were recruited into the Department of Labour. She set up her Women's Branch in the Government Buildings in Wellington. In addition to registering women seeking employment, she tried to drum up business by sending out circulars and advertising the bureau. The response from employers was not encouraging, however. In November 1895 she was promoted to be an inspector of factories, only the second women to be appointed to this position. The Women's Branch was taken over by Helen Staveley.
Margaret Scott's principal work as an inspector was to investigate factories and shops throughout New Zealand where women and girls were employed, and to ensure that accommodation, ventilation and sanitary conditions prescribed under the Factories Act 1894 and its amendments were being fulfilled. She also reported women's pay rates, hours of work and apprenticeship conditions. In 1896 nearly 8,600 factory employees, or just over a quarter, were women and girls. Over the next decade the proportion of women in factories dropped by about three per cent, but Scott's workload increased considerably as the number of workplaces to be inspected increased and the number of female factory workers doubled.
In her annual reports Margaret Scott – or Margaret Scott Hawthorne, as she signed herself after her marriage in 1898 – extolled the virtues of trade union organisation among women and the extension of state regulation of women's working conditions. She believed that 'Without organization workers can have very little power to better their economic or social condition'. She often compared the strength of unionised groups of tailoresses and women in the boot trades with the plight of dressmakers, who suffered 'through the fact that there is no uniformity or organization among them'; while tailoresses' apprenticeships and wages were regulated, dressmakers often spent their first 12 months working without wages or proper training. She drew attention to the excessive hours worked by nurses and waitresses and to the poor standard of accommodation provided for women working in restaurants and refreshment-rooms. These groups of women had neither a union nor protective labour legislation. Her own trade union apprenticeship had left her somewhat partisan; Edward Tregear, the secretary of the Department of Labour, noted that she was a 'very good officer' but her 'mannerisms' were 'not always appreciated by employers.'
Margaret Scott Hawthorne was conspicuous among women employees in the Department of Labour and the public service generally. The number of female public servants grew significantly after the turn of the century: in the Department of Labour the number rose from two in 1896 to 18 (a fifth of the staff) in 1909. For most of this time Hawthorne was the only female factory inspector employed by the department. She was one of the highest-paid female public servants, earning £190 in 1909, although this was significantly less than a male factory inspector with the same experience, and there was no further promotion available to her. It was not until 1906 that she was joined by Harriet Morison. However, Morison was transferred to the Women's Branch of the Auckland office two years later, and Hawthorne herself resigned in November 1910 at the relatively early age of 41. It was not until 1919 that the female inspectorate re-emerged.
Margaret Scott had married Mark Henry Hawthorne, a boot and shoe importer, at Wellington on 3 May 1898. They lived together only briefly, however, and in 1915 Mark Hawthorne obtained a divorce. Margaret Scott Hawthorne gave birth to a daughter about the time of her resignation from the public service. On 20 December 1916, at Papakura, she married James Smith, a farmer. She died a widow at Auckland on 1 May 1958. Margaret Scott Hawthorne was one of those who spearheaded the campaign to improve conditions for women workers. She is also notable for being one of the first women to achieve a position of status in the public service.