In 1989, Anderson married fellow prisoner and IRA member Paul Kavanagh at Full Sutton Prison. By 1993, she was one of just two female category A prisoners in England, the other being fellow republican Ella O'Dwyer. While at Durham Prison, Anderson obtained a first-class honours degree in social science from the Open University. In 1994, she was transferred from Durham to Maghaberry Prison in Northern Ireland. On 10 November 1998, Anderson was released under the terms of the Good Friday Agreement.