Sanderson's father emigrated to England before she was born, and her mother followed him before she was a year old, leaving her and her sister to be raised by their grandmother in rural Jamaica. They joined their parents in the Midlands when she was eight.
She was not academic in school, but discovered the javelin when she was 12. She won gold medals at the 1978, 1986 and 1990 Commonwealth Games, the 1984 Olympics and the 1992 World Cup.
Since retiring from competition she has been a television sports commentator and works for several charities.