[2] Her father was Edgar Bellhouse, a founding member and former chair of the liberal (white) Progressive Party, and her elder sister was renowned activist Molly Blackburn.
[2] As apartheid intensified, Chalmers and Blackburn grew disenchanted with traditional white politics, particularly after they attended the funeral of Robert Sobukwe in Graaff-Reinet in 1978.
During this period, with Blackburn and others, she reopened the Black Sash's Port Elizabeth Advice Office, through which she conducted outreach with black residents of the region and monitored human rights abuses by the apartheid government.
[3] In late December 1985, Chalmers and Blackburn were in a car accident while driving back to Port Elizabeth from Oudtshoorn with fellow Black Sash activist Diana Bishop.
[6] She served three terms, gaining re-election in 1999 and 2004, and she represented the Eastern Cape constituency.