Remarkably, Van Nispen kept a diary. What was even more remarkable was that he handed over part of his diaries from 1964-1972, at the encouragement of former Prime Minister De Jong, to the National Archives at the end of his life. Here, they remained closed for 50 years and on 1 January 2023, the diaries were allowed to be opened.
On Thursday 20 June 2024, these diaries, together with excerpts from earlier diaries (from before 1964), were published as a book. They were presented at a symposium organised to mark Thom de Graaf's retirement as Chairman of the Board of the Parliamentary History Foundation.
The symposium highlighted the importance of such scientifically edited ego documents for (political) historiography from various angles. Speakers included former civil servant Roel Bekker, who recently published a book on all SGs of the Ministry of General Affairs; CPG researcher Alexander van Kessel, one of the diary's deliverers; Frans van Nispen, the diarist's eldest son; Kajsa Ollongren, outgoing Minister of Defence and previously (2011) the first female SG of the Ministry of General Affairs and Jan Willem Brouwer, biographer of one of the nine prime ministers (Piet de Jong) for whom Van Nispen worked. Emerita Professor of Parliamentary History Carla van Baalen, also the diary's other contributor, served as chairperson for the day.