Winifred Mayo was born Winifred Monck-Mason to a British family in India. Her father was a flautist and opera producer. She trained as an actress at the Italia Conti Academy of Theatre Arts in London and took Winifred Mayo as her stage name. She was the co-director of the first professional stage adaptation of Pride and Prejudice, and also played the role of Elizabeth Bennet. A supporter of women's suffrage, in 1907 she joined the Women's Social and Political Union (WSPU) along with her mother Alice Monck-Mason. Soon afterwards she took part in a demonstration outside the House of Commons and spent six weeks in prison. In 1908, she was a founding member of the Actresses' Franchise League with Sime Seruya; other members included Edith Craig, Ellen Terry, Sybil Thorndike, and Lily Langtry. Winifred was arrested in 1909 and again in 1910 after the "Black Friday" demonstration in Parliament Square, but was discharged both times. In 1911, she was imprisoned for three weeks for taking part in the suffragist window-smashing campaign. From 1921 to 1926, she was the organizing secretary of the Six Point Group of Great Britain. She published a memoir called Prison Experiences of a Suffragette in 1908. Late in life, she recorded her recollections of her friend Emmeline Pankhurst and of smashing the windows of the tony Guards’ Club, for the BBC.