Over the years the Council grew, with increased democratic representation. The Council of 1920, included six BSAC nominees and thirteen elected members, the majority of which were part of the Responsible Government Association (RGA). The RGA wanted autonomous government for the colony within the British Empire, forming an alliance with the Labour Party to oppose one group which proposed that Southern Rhodesia become part of the Union of South Africa, and another group which wanted continued government by the BSAC.
The following year, a British Commission reported that the colony was prepared for responsible government, and that the electorate should decide whether Southern Rhodesia have their its own government or become part of the Union of South Africa. Even though the British government, the BSAC, and the South African government all favoured union, when the referendum was held on 27th October 1922, 59.4% of the votes supported responsible government, with a turnout of 78.5%. The following year, BSAC control of the colony ceased and in April 1924, the first elections were held for the Southern Rhodesian Legislative Assembly.