From Helen Suzman's Obituary:

"In a parliamentary career of 36 years, she spent only six in a party of any size. She quit the paternal United Party in 1959, frustrated that it was so wobbly against apartheid, to join a Progressive Party of 12 members that was wiped out in an election two years later. She was the sole survivor, for 13 years a one-woman opposition to the relentless consolidation of white rule. The small but determined voice of the “neo-communist” and “sickly humanist” would call out “No”—to the Sabotage Act, the Terrorism Act, the Ninety-Day Detention Law—and she would be left sitting alone in a sea of empty green benches.
"Her strength was that she knew the facts, and knew her rights. South Africa’s devotion to the Westminster parliamentary system, a figleaf of democracy over barbarism, meant that the Speaker was bound to let this “lone Prog” speak, and ministers had to answer her questions. She was allowed to bring one Private Member’s Motion a year, so she would try single-handedly to repeal the Prohibition of Mixed Marriages Act, or propose a minimum wage for blacks."
--Economist.com