 Having been governed and developed by the British South Africa Company since the 1890s , Southern Rhodesia became a self @-@ governing colony within the British Empire in 1923 , when it was granted responsible government by Whitehall . The Southern Rhodesian capital , Salisbury , was henceforth empowered to run its own affairs in almost all matters , including defence . Foreign affairs was one of the few areas reserved by the British government . As the Empire 's lone self @-@ governing colony , Southern Rhodesia was considered a sui generis case , almost on a par with a dominion . Starting in 1932 , Imperial Conferences included the Southern Rhodesian Prime Minister alongside those from the dominions , a unique situation which continued after Imperial Conferences were superseded by Commonwealth Prime Ministers ' Conferences in 1944 . 
