This piece presents an analysis written by the renown British historian Sir Robert W. Seaton-Watson on the aftermath of the Croat - Serb Agreement in fall 1939, in the time of the outbreak of the Second World War. Seaton-Watson, as he did often in those months, wrote the analysis for the British Foreign Office on the occasion of visiting Zagreb and Belgrade in fall of 1939. He regarded the political consequences of the Agreement as positive for Croatian, as well as Yugoslav politics, especially from the view point of promoting democratic practices and anti-nazi activities in the country. The Agreement helped consolidate and unite the Yugoslav political scene, which was in the interest of Great Britain and her policy of keeping up a strong and neutral Yugoslavia. The commentary to the text attempts to explain the circumstances described and point out who were Seaton-Watsons friends among Yugoslav intellectuals and how they influenced his better understanding of the Yugoslav situation, especially the Croat and Slovene questions.