In 1979, Sewell was research assistant and private secretary to National Party MP, Marilyn Waring in Wellington. In 1985 she was appointed director of the Consumer Affairs Unit and from 1986 until 1988 was head of the Ministry of Consumer Affairs. 
Socialist Action League
Sisters Overseas Service
In 1977, Sewell founded the Sisters Overseas Service in response to the Birch Amendment. In 1978, Sewell was chairperson of the Christchurch branch of Sisters Overseas Service. SOS was a pro-abortion organisation that helped women travel to Australia to obtain an abortion. Penny Fenwick was secretary at the time.
In the 1970s, Sewell had links to the Christchurch Resistance Bookshop and the Chippenham Commune.
In 1977 she was involved in United Women's Conference.
In 1981, as president of the Young Women's Christian Association, Sewell issued a press statement opposing the Springbok tour. The statement was reprinted in its entirety in the Socialist Unity Party's 13 July Tribune.
- Radio New Zealand website: Sound Archives: Elizabeth Sewell - The Interminable Son by Hamish Sewell (accessed on 27 July, 2010)