Bolkestein was the Minister for Education, Art and Science from 1939 until 1945, and was part of the Dutch government-in-exile from 1940. In early 1944 he gave a radio address from London in which he said that after the war he would collect written evidence from Dutch people relating to the oppression they had endured during the Nazi occupation. Among those who heard the broadcast was Anne Frank who had been keeping a diary for two years, which she had spent in hiding. His comment that he was particularly interested in diaries and letters, led Frank to edit what had originally been a diary kept for her own amusement. Frank later died in Bergen-Belsen concentration camp, but her partially edited diary was saved, and eventually published in 1947.