Dinsdale was a Progressive Conservative Member of Parliament from 1951 until his death in 1982, being first elected in a 1951 by-election with an upset victory to take a seat previously held by the Liberals. Dinsdale was originally hesitant about running in the by-election, and was fired by Brandon College soon after his nomination. Dinsdale won 56.9% of the vote in that by-election. During his tenure in the House of Commons of Canada, he represented the riding of Brandon for one year in 1951 until it was merged with the neighbouring riding of Souris to form Brandon—Souris. He held Brandon-Souris from 1952 until his death in 1982, winning 11 consecutive election victories. At the time of his death he was the Dean of the House - the longest-serving Member of Parliament. During his period as MP, he was the parliamentary assistant to the Minister of Veterans Affairs in 1957, and parliamentary secretary to the same minister in 1960. He then joined the Cabinet of John Diefenbaker as Minister of Northern Affairs and National Resources from 1960 to 1963. He was also acting Minister of Mines and Technical Surveys for a few months in 1961. In 1963, while serving as Minister of Northern Affairs and National Resources he chaired the "Resources for Tomorrow" conference, which led to the establishment of a Department of the Environment. Dinsdale worked tirelessly for many causes, including First Nations, international human rights, immigrant Canadians and most notably disabled persons. He was vice-chair of the Special Committee on the Disabled, whose work led to many improvements in services for disabled Canadians, and worked with many international governments and organizations to improve the lives of the disabled everywhere, and in 1981 was Canada's delegate to the United Nations for the International Year of Disabled Persons.
Honours
The Walter Dinsdale Award, which recognizes outstanding achievement in developing technologies that improve the lives of the disabled, is named in his honour. Dinsdale was awarded a Doctor of Laws degree by Brandon University and a Doctor of Humanities degree from Richmond College in Toronto for his works with disabled people.
Death
He died from kidney failure in 1982, after suffering a stroke about two months before his death. He is buried in Brandon. Following his death, he was eulogized in the House of Commons of Canada, following which the house was adjourned for the day in tribute.
Family
Walter married Lenore Gusdal, and had 5 children: Gunnar, Greg, Elizabeth, Eric and Rolf. His son Rolf ran as a Liberal Party of Canada candidate in a federal by-election in Brandon—Souris in 2013, losing narrowly to Larry Maguire.
