As a Substitute, Mrs Seweriin was one of the first ten women "members" of the Assembly accredited in 1949 - and the only Norwegian. It is interesting to note that the number of women has risen from 3% in 1949 to 46% in 2023. Ms Seweriin was rapporteur for credentials at the second session of the Assembly in 1950.
Mrs Seweriin had been a member of Oslo City Council from 1937 until the Second World War broke out, and also served briefly in 1945. She and her husband had been active members of the Norwegian resistance movement, among others, starting the illegal newspaper Fri Fagbevegelse. After the war she was a member of the Labour Party secretariat for women from 1945 to 1971—from 1953 to 1963 she chaired the secretariat, and was a member of the Labour Party's central committee.
She was elected as a member of the Parliament of Norway in 1945. When she stepped down in 1969, her time of 24 years as a parliament member was a record for a woman in Norway. She was the Norwegian Minister of Social Affairs from 1953 to 1955.
The project “75 women in 75 years of Council of Europe history” is organised by the Delegation of the European Union to the Council of Europe with the Council of Europe and the Permanent Representations of the Kingdom of the Netherlands and the United Kingdom.