Brookes was involved with a wide range of organisations, and according to
The Sydney Morning Herald was "never merely a figurehead or a sleeping partner in any enterprise with which she allows her name to be associated". She lived in Washington, D.C., from 1929 to 1931, during her husband's service as
Commissioner-General to the United States. Brookes was elected as a
justice of the peace in 1934. She was the inaugural vice-president of the
Anti-Cancer Council of Victoria, from 1936 to 1966, and was a foundation member of the
University of Melbourne's boards of physical education (1938–1970) and social studies (1941–1967).
Political involvement Brookes shared many of her father's political beliefs, as did her husband. As an able public speaker and political organiser, she became "her father's most valuable lieutenant in organising women for the liberal cause". In 1909, she became the honorary secretary of the Commonwealth Liberal Party (CLP), an organisation which Deakin had founded to support the
"Fusion" Liberal Party he created in federal parliament. The CLP was later absorbed into the People's Liberal Party, where she held a similar position. Brookes was active in policy formation, presenting policy papers on
equal pay for equal work, "national social insurance", "delinquent parents", and the role of women in politics. In 1913, she attended a forum chaired by
Vida Goldstein, and seconded a motion calling for the federal government to implement
equal pay for equal work. Brookes campaigned for the "Yes" vote during the
1916 and
1917 referendums on conscription, embarking on "an ambitious public speaking trail" in country Victoria. After the creation of the
Nationalist Party in 1917, she also held leadership roles in the National Union and National Federation. However, she suspended her active involvement in politics after her father's death in 1919. In 1925, Brookes returned to politics as a substitute for her ill husband, organising finances and election material at the
1925 federal election. Her liberal views had previously brought her into conflict with the more conservative
Australian Women's National League (AWNL), but she eventually joined the league and became a vice-president. She assisted
Elizabeth Couchman in bringing the AWNL into the new
Liberal Party of Australia in 1944, and became one of its founding members and "a matriarch of the party that she and Herbert regarded as the philosophical heir of her father's".
National Council of Women Brookes was first elected to the executive of the
National Council of Women of Victoria in 1912. She was re-elected to the executive in 1934, then elected vice-president in 1936 and president in 1938. She was one of the Australian delegates at the
International Council of Women's 50th anniversary conference, held in Scotland in 1938. As a delegate to the
National Council of Women of Australia (NCWA), Brookes chaired its press, arts and letters and peace and international relations committees for a number of years. She was elected national president in 1948, serving until 1953. During her term as president, the organisation lobbied for equal pay and abolition of the
marriage bar, and advocated for the interests of migrants and indigenous people. Brookes represented the organisation at the 1951 national inflation conference and as a member of the Advisory Committee on Import Licensing Control. She was appointed a life vice-president of the NCWA at the end of her term as president. ==Personal life==