[1] Milne was the daughter of former Mayor of Toronto and Co-operative Commonwealth Federation (CCF) Member of Provincial Parliament (MPP) William Dennison and granddaughter of Isaac Bainbridge, early labour organizer and pacifist.
She owned Flowertown Antiques (1972–89), featuring early Canadian pressed glass, a field in which she was a known expert.
Milne was involved in community activities and charitable organizations, serving as President of the North Peel unit of the Canadian Cancer Society in the 1980s and as residential coordinator for the Heart and Stroke Foundation of Ont.
In the Senate, she served as chair of the Legal and Constitutional Affairs Committee, and waged a seven-year campaign from 1998 to 2005 to allow historical census data to be released to the public.
She also served as Chair of Committee on Rules, Procedures and the Rights of Parliament when it successfully recommended creation of the position of Senate Ethics Officer.
[citation needed] Milne served as Senate Vice-Chair of the National Liberal Caucus from 2006–2009 and also was President of the Canada-Europe Parliamentary Association from 2004-2008.