Isabel Carruthers was a member of the National Union of Women's Suffrage Societies (NUWSS) and the Conservative and Unionist Women's Franchise Association (CUWFA), who lived at Holmains, Wellington Square, Cheltenham; she was a signatory of the 1912 book presented to Sir James Agg Gardner, in recognition of his support for women's suffrage (Gloucestershire Archives, catalogue reference D5130/6/6).

On the 1911 census she was listed as a widow, and her occupation was given as "private means". Her husband had been an Indian army officer.

She died on 30 October 1921.