Paper was dedicated to less known history of the first double-decade of Kosovo and Metohija autonomy. It describes the origin of autonomy, uprising since 1943 in minds of Communist Party of Yugoslavia (KPY) leaders, analyses the limits for its functioning emphasizing the fact, that during the first two decades the whole sphere was managed by Yugoslav Secret Police. The paper elucidates the influence of general assembly of the Central Committee (CC) of the KPY, which took place at Brioni, 'disclosing' deformations in Secret Police activities. This resulted in loosening of circumstances even in south Serbian province and its unprecedented advancement. The author stems from extensive secondary literature, predominantly of Serbian (but also Croatian, American, etc.) provenance; however, the roots are represented by studying the primary resources. Subject matter concerns both official documents of the KPY, and documents from the archive of the League of Communists of Serbia (LCS), being kept in the Archive of Serbia located in Belgrade. Especially archive funds of the LCS CC, treasuring the documents of Investigation Commissions established by LCS CC after the Brioni general assembly.