[1] Thyberg served as first legation secretary in Copenhagen in 1933 and was chargé d'affaires ad interim in Cairo in 1936.

Thyberg was director of the Political Department at the Foreign Ministry in Stockholm from 1941 to 1944 and was minister plenipotentiary, chargé d'affaires and the Swedish government's agent for monitoring the Greece Commission's aid activities in Athens from 1944 to 1948.

As the Germans did not permit any foreign diplomatic representatives, Minister Thyberg initially held the title of Swedish Consul General and only gained full diplomatic status after Greece's liberation and the Germans' withdrawal in October 1944.

Minister Thyberg conducted his official duties at the Dutch legation, whose interests Sweden represented.

During the activities associated with these protective missions, Minister Thyberg, thanks to a considerable level of understanding from SS General Walter Schimana, who was then the highest-ranking German military officer in Athens, managed to liberate around 50 Jews from captivity and return them to their homes.