[2][4] Ditlev-Simonsen developed one of the largest shipping companies in Norway, together with three of his sons.

He was also active in organizational work, and was a board member of the Norwegian Shipowners' Association, Kristiania Rederiforening, Oslo chamber of commerce and the Port Board of Oslo.

[2] He was elected member of the municipal council of Kristiania, and served as vice mayor 1914–1915.

[5] In this position he was quite busy with the 1914 Jubilee Exhibition at Frogner and Skarpsno.

[2] Ditlev-Simonsen was an eager sports sailor, and had the two cutters Vav and Isabel Alexandra.