He is known as editor-in-chief of Tønsbergs Blad from 1954 to 1977 (until 1963 joint with Realph Norland) and for the column "SORRY" in Aftenposten, which he wrote from 1946 to 1996.
[5] Tidens Tegn was permanently discontinued in 1941 because of the Nazi occupation,[6] but in 1942 Mitsem was asked by Realph Norland to work in the newspaper Tønsbergs Blad, which had ties to the Conservative Party.
[7] Mitsem reached out to an even larger audience with the column "SORRY e. Trollhaugens Tass" in Aftenposten,[7] which was Norway's largest circulated newspaper until 1981.
The column took the shape of an eponymous cocker spaniel; the dog figure was chosen from a series of candidates presented by Egil Meidell Hopp.
[9] Mitsem was also a theatre critic for Høyres Pressebyrå, which delivered articles to a large number of conservative newspapers.