1942: Gen MacArthur moved HQ to Brisbane. Central Bureau moved in Sept.
Info from www.ozatwar.com:
Central Bureau was a joint American-Australian Sigint organisation which was established on 6 April 1942 under the command of Major General S. B. Akin with its headquarters based in Melbourne. General MacArthur advised Washington of his decision in a dispatch on 1 April 1942. He described the role of the group as "the interception and cryptanalyzing of Japanese intelligence." The name Central Bureau was chosen so as to convey no information whatever to outsiders as to the nature of the work being done. Major Abraham "Abe" Sinkov, a mathematician, was appointed Assistant Director of Central Bureau.
Central Bureau was attached to the HQ of the Allied Commander of the South West Pacific area. The other unit was the joint RAN/USN Fleet Radio Unit, Melbourne (FRUMEL), which was subordinate to the Commander of the USN 7th Fleet.