He served in the Legislative Assembly of Manitoba from 1927 until his death, and was a cabinet minister in the governments of John Bracken, Stuart Garson and Douglas Campbell.
He later attained a Bachelor of Arts degree from Manitoba University, and worked as a barrister-of-law, after studying in the office of future Prime Minister Arthur Meighen.
McLenaghen was returned by an increased majority in the 1936 provincial election,[1] the first in which the Conservative Party was led by Errick Willis.
He was re-elected in 1941, 1945 Manitoba general election and 1949[1] over candidates of the CCF, though in 1945 he almost lost the coalition nomination to Frank Simmonds.
His death in 1950 deprived the pro-coalition forces in the party of their most powerful voice, and the Conservatives in fact left the coalition soon after.