Mary Ann (known as Marion) Hanover was born in Preston, Somersetshire, England, probably on 8 September 1835, the daughter of Elizabeth Stenner and her husband, Robert Hanover, a licensed victualler. She was working as a milliner when she married Joseph Hatton, an accountant, at Bath on 7 October 1855. Before and after her marriage she engaged in Sunday-school work and the temperance campaign conducted by the Band of Hope Union. The Hattons went to Amsterdam to further the temperance cause by establishing the first lodge of the Good Templars there.
It is not known when Marion and Joseph Hatton arrived in New Zealand, but Marion first publicly identified herself with the campaign for the enfranchisement of women when she chaired a pro-suffrage meeting in Dunedin on 12 April 1892. The behaviour and verbal attacks of the mayoral candidate, MHR and head of the liquor lobby, H. S. Fish, goaded the Dunedin suffragists to remove the prohibition issue from the suffrage campaign. The Women's Franchise League was established a fortnight later, and Hatton became president. She was backed by her husband, who, as secretary of the local prohibition league, had already made public its resolution to the government requesting that women's enfranchisement be incorporated in the Electoral Bill. Marion Hatton's work in the church and the temperance movement gave her a common ground with many suffragists, but because the WFL had made winning the franchise its sole concern, the movement had become attractive to a broader spectrum of women.
Both Marion Hatton and Harriet Morison, then secretary of the Tailoresses' Union of New Zealand in Dunedin, stressed that the key to the league's campaign was organisation. Collecting signatures for the suffrage petitions circulated each year from 1891 to 1893 was seen as crucial for putting pressure on the government to enact legislation. Hatton explained the league's strategy: 'we shall want all the help we can command, and all classes and conditions of women should be made available…we shall hope to be in a position to map out the whole of the city and suburbs for our canvassers'. Dunedin was the largest city in New Zealand in the 1890s, and therefore an important centre in which to make the petition successful.
With Helen Nicol, the WFL's secretary, Marion Hatton also introduced the league's tactics to other centres. The pair travelled to townships in South Canterbury, Otago and Southland to speak at suffrage meetings. Despite having a soft voice, Hatton was the league's principal speaker. On these visits she emphasised the importance of a thorough canvass for the petitions. The league's efforts were rewarded. Many women outside the temperance movement, especially those unionised by Morison, supported the petitions and Otago returned by far the largest number of signatures.
Marion Hatton made women's suffrage the key issue of the mayoral election in Dunedin in 1892. Of H. S. Fish she stated: 'we are pledged as a League to vote down the man who had done the worst he knows to injure our cause in the House of Representatives, and who has insulted the women of this colony, as no other man ever dared to do before.' An exchange between the two took place in the newspaper, with Marion Hatton exhorting those women with the municipal vote to favour 'the candidate most likely to defeat Mr Fish.' Fish was unsuccessful, and later admitted that the women had been shrewd tacticians in distributing a circular the day before the election when he had no time to reply. The vote of women property owners was recognised as being decisive and 'a perfect answer' to those who were sceptical of women's interest in and commitment to politics.
After New Zealand women had won the right to vote in parliamentary elections, Marion Hatton continued to develop her ideas on women's rights. While many of her contemporaries saw prohibition as the most important issue, her main aspiration was to redress the inequality of women before the law. Her particular concern was that women be given the same pay as men for performing the same tasks equally well. She also helped to initiate the National Council of Women of New Zealand, and in 1896 attended the inaugural conference in Christchurch.
Hatton remained president of the Women's Franchise League, which provoked controversy in 1895 by publishing a political manifesto. Its aims were 'the consolidation of the political rights already won, the extension of the privileges opened up by our present political position, and the furtherance of all those claims by which we seek to place woman in her rightful position amongst men.' There was also a practical aspect to the WFL's beliefs. During the winter of 1895 it opened and maintained soup kitchens for the unemployed of Dunedin.
Marion Hatton suffered from heart disease, and her hard work for charitable projects may have adversely affected her health. She died in Dunedin on 6 June 1905, survived by her husband, five sons and a daughter.