The Federal Prime Minister held the External Affairs portfolio throughout and that of Defence until Jun 1959. The Federal Intelligence and Security Bureau (FISB) came under the Prime Minister. Its activities on the internal front and the use of Federal military forces to support territorial governments in the maintenance of law and order overlap. Likewise, immigration and deportation, strikes, and industrial unrest attracted the attention of the FISB. In the realms of external affairs, the Bureau was interested in developments in the (Belgian) Congo (Democratic Republic of the Congo) and the Portuguese colonies because of their potential effect on the Federation.

Welensky was acting Minister of Defence in the absence of Lord Malvern at various dates between 1954 and 1956. As such, and also as deputy to the Federal Prime Minister, he received various security and defence material barred to his colleagues. Welensky, like his predecessor as Federal Prime Minister, held the Defence portfolio until relinquishing it to Caldicott in Jun 1959.