At the
1931 general election, Thorby won the federal seat of
Calare, which he held until 1940. He was a Minister without Portfolio from November 1934 to November 1937 in the
Lyons government, entitled Assistant Minister for Repatriation (1934–35),
Minister for War Service Homes (1935–36) and Assistant Minister for Commerce (1935–37). In November 1937, Thorby was elected deputy leader of the Country Party, defeating
John McEwen by a single vote on the second ballot. He subsequently served as
Minister for Defence from November 1937 to November 1938 and Minister for Works and
Minister for Civil Aviation from November 1938. During this period he initiated a program of adding annexes to existing factories to accelerate armaments production, but this program failed to spend even budgeted funds. In April 1939, he left the ministry when the Country Party refused to take part in the
Menzies government. With the formation of a
coalition government in March 1940, Thorby became
Minister for Health and
Postmaster-General. ==Later years==