 Bennet was present at the founding of the Women's Tax Resistance League becoming a tax resister herself and in 1908 was a WFL delegate to the Amsterdam conference of the International Woman Suffrage Alliance.Benett joined the New Constitutional Society for Women's Suffrage (NCSWS) and was Treasurer of the Women's Freedom League from 1909 until her resignation in 1910 from which time she devoted her efforts to the more militant Women's Social and Political Union.She was one of 120 women arrested for demonstrating outside the House of Commons on 'Black Friday' in 1910 when many women were seriously assaulted by the police.