He served in World War I, and subsequently worked as a cash grain broker.
[1] This was a two-member constituency at the time, and Fennell defeated Cooperative Commonwealth Federation candidate David Turner for the second seat.
He served as a backbench supporter of Douglas Campbell's government during his time in the legislature.
The Liberal-Progressives lost to the Progressive Conservatives in the 1958 election, and Fennell lost to future Premier of Manitoba Sterling Lyon[1] by 1,323 votes in the redistributed constituency of Fort Garry.
He returned to municipal politics and served as mayor of Fort Garry again from 1960 to 1967.