Montague was not a candidate in the 1915 provincial election, and Prout defeated his new Conservative opponent[1] by 541 votes to win a seat in the legislature.
The Liberals won a landslide majority government in this election, and Prout served as a backbench supporter of Tobias Norris's administration for the next five years.
In 1917, he introduced the Rural Credits Act which provided for the establishment of rural credit societies that could obtain short term loans on behalf of members to purchase seed, livestock, implements, machinery and other supplies.
Prior to this election, a change in Manitoba's electoral system redesigned Winnipeg as a ten-member constituency, with members chosen by a single transferable ballot.
Prout attempted to return to the legislature in the 1927 provincial election, running as a Liberal candidate in the Fisher constituency.