Winifred Margaret Aumann was born in 1923 to Frederick Benjamin Aumann, an orchardist, and Marguerite Gertrude Pettingill. She was educated at Narre Warren State School and Dandenong High School, and later completed certificates in Nursing, Midwifery and Child Health. Winifred worked as a nurse in Melbourne from 1944 until 1946, when she moved to Western Australia and worked in hospitals in Busselton and Narrogin. In 1947 she married Mervyn Piesse, a farmer at Wagin in Western Australia, about 230 kilometres south-east of Perth.

Winifred Piesse joined the Country Party in 1948 and worked as both branch and divisional secretary. When her husband died in 1966, she returned to nursing and also managed farms in the Wagin area. She was the first woman to be elected to the Wagin Shire Council, in August 1971, and also became a Justice of the Peace in that year.

Winifred Piesse became the first woman to represent the Country Party in the Western Australian Parliament when she was elected to the Legislative Council for a six year term, beginning in May 1977. Her extensive experience in nursing ensured that health matters were high on her Parliamentary agenda. She was particularly concerned about issues affecting children and youth, and also urged the government to urgently fund research into breast cancer, especially its high incidence in young mothers.

Piesse lost her seat in 1983, her preferences helping to elect the Liberal candidate. After leaving Parliament Piesse served for three years on the local hospital board, and maintained her strong links with community organisations including the Country Women's Association, Farmer's Union, and the St. John's Ambulance Brigade.  

Sources used to compile this entry: Black, David and Bolton, Geoffrey (eds), Biographical Register of Members of the Parliament of Western Australia, Vol. 2, 1930-1990, Western Australian Parliamentary History Project, Perth, Western Australia, 1990; Black, David and Phillips, Harry, 'Making a Difference: Women in the West Australian Parliament 1921-1999', Parliament of Western Australia, Perth, Western Australia, 2000.