[1][2] After being called to the bar, he joined a practice in Orangeville, where he also held municipal offices as mayor and councillor.

Shortly after being created a king's counsel in 1903, Walsh moved south to Calgary, where he quickly established another practice.

[3] His father, Aquila, born in Charlotteville Township,[3] initially worked as a civil engineer, later serving as Deputy Registrar for Norfolk County[3] and as a member of the House of Commons of Canada.

[4] In 1889, he was elected a town councillor, serving on assessment, finance, public works and printing committees.

[6] One of his first cases, in 1904 was defending a man accused of horse theft, being heard by the Chief Justice Arthur Sifton and the Supreme Court of Alberta.

[7] The most notable trial that Walsh presided over was that of Emilio Picariello, for the murder of Alberta Provincial Police Constable Stephen Lawson.

After the murder charge was laid by Attorney General of Alberta John Edward Brownlee, Picariello and his accomplice, Florence Lassandra were found guilty of their crimes and were sentenced to hang.

[6] He ran in a 1906 by-election for the provincial constituency of Gleichen, but was unsuccessful, losing by just over 100 votes to Liberal Ezra Riley.

[10] Most of Walsh's everyday duties as lieutenant governor consisted of attending official functions and supporting charitable causes.

His daughter Marguerite married Dr. George Robinson Pirie (1879–1938), a prominent children's doctor and member of the Royal College of Physicians (1931).

[4] William Legh Walsh later married Bertha Main Barber, widow of a Royal Navy commander, on April 22, 1931.

[12] An avid golfer, Walsh founded a seniors' golf tournament named for him that still is held presently, alternatively in Edmonton and Calgary.

[14] William L. Walsh died on January 13, 1938, of heart failure following a stroke in Victoria, British Columbia.

[14] William A. R. Kerr, president of the University of Alberta said of him, "All who knew [Walsh] … not only respected him for his gifts of mind and character but loved him as a fine warm-hearted human being.

"[14] L. Ralph Sherman, an Anglican bishop of Calgary described his legacy as "a record of integrity, devotion to duty and service which will be an inspiration.