Question: What is the birthdate of this British political activist and leader of the British suffragette movement who helped women win the right to vote and who tightly controlled the membership and policies of Women's Social and Political Union?

Context articles: Gertrude Harding
Flora Drummond
Christabel Pankhurst
Jessie Stephen
Women's Social and Political Union
Charlotte Marsh
Mabel Capper
Women's Printing Society
Edith How-Martyn
Emmeline Pankhurst

Gertrude Menzies Harding (1889-1977) was a suffragette born on a farm in rural Canada.
 She happened to arrive in London, England, in 1912 at the height of the militant suffragette movement, which she quickly joined, one of only a handful of Canadians to do so.
 Gert Harding remained as one of the highest-ranking and longest-lasting members of this organization, the Women's Social and Political Union.
 British women were granted a partial vote in 1918.
Flora McKinnon Drummond (née Gibson, later Simpson), (born 4 August 1878 in Manchester– died 7 January 1949 in Carradale), was a British suffragette.
 Nicknamed The General for her habit of leading Women's Rights marches wearing a military style uniform 'with an officers cap and epaulettes' and riding on a large horse, Drummond was an organiser for the Women's Social and Political Union (WSPU) and was imprisoned nine times for her activism in the Women's Suffrage movement.
 Drummond's main political activity was organising and leading rallies, marches and demonstrations.
 She was an accomplished and inspiring orator and had a reputation for being able to put down hecklers with ease.
Dame Christabel Harriette Pankhurst, DBE ( ; 22 September 1880 – 13 February 1958), was a British suffragette born in Manchester, England.
 A co-founder of the Women's Social and Political Union (WSPU), she directed its militant actions from exile in France from 1912 to 1913.
 In 1914 she supported the war against Germany.
 After the war she moved to the United States, where she worked as an evangelist for the Second Adventist movement.
Jessie Stephen, MBE (19 April 1893 12 June 1979) was a twentieth-century British suffragette, labour activist and local councillor.
 She grew up in Scotland and won a scholarship to train as a teacher.
 Family finances dictated otherwise, leading to her becoming a domestic worker at the age of 15.
 She became involved in national labour issues as a teenager, via organisations such as the Independent Labour Party and the Women's Social and Political Union.
 After moving to Lancashire and London she visited the United States and Canada, where she held meetings with the public including migrant English domestic workers.
The Women's Social and Political Union (WSPU) was the leading militant organisation campaigning for Women's suffrage in the United Kingdom, 1903–1917.
 Its membership and policies were tightly controlled by Emmeline Pankhurst and her daughters Christabel and Sylvia (although Sylvia was eventually expelled).
 It was best known for hunger strikes (and forced feeding), for breaking windows in prominent buildings, and for night-time arson of unoccupied houses and churches.
Charlotte "Charlie" Marsh (1887-1961) was a British suffragette.
 In 1907 she joined the Women's Social and Political Union, but did not become active as an organizer until 1908, after completing her training as a sanitary inspector.
 In June of that year she was imprisoned in Holloway for a month on charges of obstruction.
 The next year she was again imprisoned for heckling Prime Minister Asquith and became one of the first suffragette hunger strikers to be forcibly fed.
 During World War I she worked as a mechanic and chauffeur for Lloyd George, whilst continuing her activism.
Mabel Henrietta Capper (23 June 1888 – 1 September 1966) was a British suffragette.
 She gave all her time between 1907 and 1913 to the Women's Social and Political Union (WSPU) as a 'soldier' in the struggle for women's suffrage.
 She was imprisoned six times, went on hunger strike and was one of the first suffragettes to be forcibly fed.
The Women's Printing Society was a British publishing house founded in either 1874 or 1876 by Emma Paterson and Emily Faithfull with the company being officially incorporated as a cooperative in 1878.
 The company played an important role in British Suffragette movement, both through its publication of feminist tracts and in providing employment opportunities for women in a field that had previously been restricted to men.
 The house was set up to allow women to learn the trade of printing, and provided an apprenticeship program.
 Women worked as compositors, and as of 1904, it was one of the few houses where they also did the imposing: ordering the galley proofs so that when folded, the front and back pages aligned properly.
 As of 1899, the company employed 22 women as compositors.
 The manager, proof-reader and bookkeeper were also women.
 Men held the tasks of "pressmen and feeders".
 The women apprentices earned a wage "considering the hours (9 to 6.30), etc., this is better pay than even highly-educated women can sometimes secure."
 Some of the initial employees came from Faithful's Victoria Press.
 The Board of Directors included Sarah Prideaux, Mabel Winkworth and Stewart Duckworth Headlam.
 Elizabeth Yeats studied for a brief time at the Women's Printing Society, before returning to Ireland and starting the Dun Emer Press.
Edith How-Martyn, née How (1875, London -1954, Australia) was a British suffragette and a member of the Women's Social and Political Union (WSPU).
 She was arrested in 1906 for attempting to make a speech in the House of Commons.
 This was one of the first acts of suffragette militancy.
Emmeline Pankhurst (née Goulden; 15 July 1858 – 14 June 1928) was a British political activist and leader of the British suffragette movement who helped women win the right to vote.
 In 1999 "Time" named Pankhurst as one of the , stating "she shaped an idea of women for our time; she shook society into a new pattern from which there could be no going back".
 She was widely criticised for her militant tactics, and historians disagree about their effectiveness, but her work is recognised as a crucial element in achieving women's suffrage in Britain.