Sometime in the early 1910s, the young artist Helen Saunders made a tiny watercolour drawing of a group of figures trapped in an enclosed space. The drawing is semi-abstract, as is much of Saunders' work of that time – she was a signed-up member of the Vorticist Group who were bringing a new, shocking, hard-edged and violent aesthetic to British art.

The figures appear to be women: there are the rudimentary signs of breasts and hips, and one has a pinkish dress and a fall of long hair. The space they are held in is stifling – the ceiling appears to be only as tall as they are, the walls close in. Though the work was untitled, it has become known since as Female Figures Imprisoned, and therein lies a mystery: why would Helen Saunders paint such a subject at this moment?

The answer may lie in her friendship with a woman who was both an artist and a suffrage activist and is now little known – Katie Gliddon.

Gliddon was a painter of flowers, seemingly a conventional subject, though she did not paint grand arrangements of choice blooms (as artists tended to do, from the Dutch golden age to modernists such as Renoir and Gauguin) but rather flowers, both cultivated and wild, brought together in straggling groups, giving her attention to their imperfections and the tendency of nature to refuse neatness and order.

Saunders may have first met Gliddon when they were both briefly students at the Slade in the early 1900s, but they encountered each other again at that vanishingly rare thing, an art school founded and run by a woman that appeared in the London suburb of Ealing in autumn 1903. The Art Guild (as it was known) was set up by Rosa Waugh, artist and writer, and sister of another artist – Edna who, when she married in 1901, became Edna Clarke Hall.

This group of women – Saunders, Gliddon, Waugh and Clarke Hall – remained involved in each other's lives as the turbulence of the late 1900s and early 1910s played out. The antagonism between those who wanted women to have the vote, and the forces of law and order upholding the establishment position (i.e. that this should never happen), was coming to a head.

Frustrated at the lack of progress, in 1903 a new, more aggressive, suffragette organisation was formed: the Women's Social and Political Union (WSPU), which Katie Gliddon joined. Militant action meant attacking property, invading government buildings and marching. In 1912, Gliddon was imprisoned in Holloway for taking a hatchet to a post office window in London's well-heeled Wimpole Street.

While she was in prison, Gliddon kept a secret diary. She was not supposed to have writing implements but had smuggled them in sewn into the lining of her coat and wrote and drew her journal in the margins of a copy of Shelley's poems. The pencil sketches she made of her surroundings in Holloway likely kept her sane, exercising her vocation as an artist when that had been forbidden, and also giving her the chance to retain some sense of control over her surroundings.

She would write about how the glimpse of a flower in the prison garden helped her, and among her papers is a drawing of a rose (again with the emphasis on its imperfections) which she gave to Helen Saunders.

Although Saunders did not carry out militant actions like her friend Gliddon, she was also a supporter of the suffragettes. Along with Gliddon, she went on the great Procession of Women through central London in 1910, which was a march of hope that the new King, George V, would herald a new age of women's enfranchisement.

There are hints as to Saunders' sympathies in her watercolour drawing of women in prison which is perhaps, then, a reference to her friend's time in Holloway.

A pair of drawings she made of a mother and child with a distinctive wooden elephant toy may have been made by the East London Toy Factory, a business enterprise started by a federation of suffragettes, including Sylvia Pankhurst, to give work to unemployed women.

While no portraits of Katie Gliddon by Rosa Waugh survive, her sister Edna Clarke Hall made a whole series of fascinating portrait drawings of the suffragette.

1912, pencil and watercolour by Edna Clarke Hall (1879–1979)

Gliddon is shown in pencil and watercolour, the fluidity of the medium captures her in fleeting moments, intense in expression, not posing in a studio but immersed in the real world. In fact, drawing was the medium in which these women chose to work most for this reason.

Although by the 1900s and early 1910s drawing had come to be seen as an art form entire unto itself, not merely an adjunct to more imposing and 'finished' works in other media, there was something more about drawing that mattered to this group. It was the most democratic medium, cheap in materials, not requiring a studio space, portable, immediately responsive to experience without the filter of reworking. You could even do it (secretly) in your prison cell.

If we compare Clarke Hall's portrait of Katie Gliddon, and a portrait of Gliddon by another suffragette (and distant relative) Helen Spanton, the motive for favouring drawing above all becomes clearer still.

Spanton's oil painting is beautifully executed, and it is true Gliddon is shown with books and pictures as the cultured woman she was, but it is heavy and unwieldy. It looks like a work from a previous century and Gliddon, a sitter from a past age. In Clarke Hall's drawings of Gliddon, though, the simplicity and flexibility of the medium creates a feeling of freedom and spontaneity, a sense of vitality and energy which speaks of women's force and potential in what they hoped would be a new age of possibility.

Alicia Foster, art historian, curator and novelist

This article is drawn from research for her new book, The Real Bohemians, coming from Virago in early 2027

This content was funded by The Bridget Riley Art Foundation