During the remainder of her life, Harriet Boomer performed volunteer work associated with the Church of England and was an active public speaker. She served as a member of the school board of London, Ontario, where she lived, and as president of the Toronto Local Council of Women (TLCW) circa 1900. She was a prominent member of the National Council of Women of Canada, which she helped to found in 1893. She was described as displaying "racy humor and sound common sense" at their meetings. She was regarded by Ishbel Hamilton-Gordon, Marchioness of Aberdeen and Temair as a personal friend and “a great feature in our National Council, for her tact & sense of humour has helped us over many a rough place.” She served as President of the London Council and Vice-President for Ontario. At some point after Dean Boomer's death, she published "Little Miss Ellerby and her big elephants: respectfully dedicated to all whom it may concern", a juvenile "dream" that is really about reducing parish debt.