Career
At the 1929 general election, McKinlay was elected as Member of Parliament for Glasgow Partick. He was defeated in 1931 and was unsuccessful when he stood again in 1935. He was re-elected in 1945 and when that constituency was abolished at the 1950 general election, he was returned for the new West Dunbartonshire constituency, holding that seat until his death one month later, aged 63.