In 1940 Maclay was elected in a wartime by-election as
Member of Parliament (MP) for
Montrose Burghs. During the
Second World War, he led the British
Merchant shipping Mission to Washington, D.C., leading to his appointment to the
Order of St Michael and St George as a Companion (CMG) in the
1944 Birthday Honours. In 1945 he briefly served as
Parliamentary Private Secretary to the
Minister of Production. He retained his Montrose seat at the
1945 general election. During the 1945 to 1951 Labour government, he led the National Liberals in the House of Commons. The Montrose Burghs constituency was abolished for the 1950 general election, and Maclay was instead returned for
West Renfrewshire, a seat he held until 1964. He served under
Winston Churchill as
Minister of Civil Aviation and
Minister of Transport between October 1951 and May 1952. In 1952 he was admitted to the
Privy Council. Maclay remained out of office until October 1956 when he was appointed
Minister of State for the Colonies by
Sir Anthony Eden. When
Harold Macmillan became Prime Minister in January 1957, he was made
Secretary of State for Scotland with a seat in the cabinet. He continued in this post until July 1962, when he was a victim of the "
Night of the Long Knives", when one-third of the Cabinet lost their ministries. In 1964 Maclay was raised to the peerage as
Viscount Muirshiel, of Kilmacolm in the County of Renfrew. He had been made a
Member of the Order of the Companions of Honour in 1962 and was made a
Knight of the Thistle in 1973. From 1967 to 1980 he served as
Lord-Lieutenant of Renfrewshire. ==Personal life==