McLagan was born in the Scottish village of Mid Calder, Midlothian, and left school at fourteen to work in the West Calder mines. He emigrated to New Zealand in 1911 and settled in Greymouth. He worked in the Grey Valley mines before briefly moving to Brunner, but he moved back to Greymouth in 1938. In 1940 he shifted again to Rangiora before finally moving to Christchurch in 1947. He was an active trade unionist all his life. In 1927 he was elected as the first Secretary of the United Mine Workers of New Zealand, holding the position until 1935. In 1937 he was elected as the inaugural President of the New Zealand Federation of Labour until 1946 when he resigned.
Political career
His political career began in local-body politics. He was a member of both the Greymouth Borough Council and Brunner Borough Council. McLagan was appointed to the Legislative Council in 1942 by Prime Minister Peter Fraser until he resigned from it in 1946 to contest a seat in the lower house. From 1944 to 1947 he was Leader of the Legislative Council. During World War II, from 1942 to 1946, he was Minister of National Service and Minister of Industrial Manpower. Following his resignation from the Legislative Council he was elected to the House of Representatives as member for the Riccarton electorate from the 1946 general election to 1956, when he died. Following the 1946 election he was appointed by Fraser as Minister of Labour, Minister of Immigration, Minister of Employment and Minister of Mines. Following Labour's defeat at the 1949 general election he was a member of the opposition frontbench under first Fraser and later Walter Nash. In 1951 he was nominated to stand for the deputy leadership of the party, but he declined the nomination. A dour, squarely-built Scot, he was self-educated and well-read, and could write shorthand. He was grim and aloft; his speeches were cold, logical and often bitter; and some civil servants and others thought he had the best brain in Cabinet.
Death
McLagan was hospitalised in early August 1956 with a chest complaint. He died on 4 September 1956, survived by his wife, two sons and two daughters.
Family history
McLagan was married to Sophie McLagan. They had two daughters and two sons. The McLagan Family had a bach in the lower Boyle River area of the Lewis Pass in North Canterbury, which was built on a lease property. The McLagan bach was moved and rebuilt by Jock McLagan on an upper plateau in the early 1970s. Often referred to as "the hut", the bach had been given the name of "Toad Hall" by J.C. McLagan. It formed the centre of McLagan and Sullivan family holidays for many years, subsequent along with the Dean's family. The Deans family also had a bach on the same river flat just above the Boyle River. Fishing and hunting were the main holiday pursuits of both families at the time. Angus McLagan collected a large number of ex-parliamentary library books and other records, primarily books written in Latin, which remained with Sophie McLagan until her death in 1989. Angus McLagan died one year to the day before the birth of his first grandchild, first son of Cissie Agnes and John Henry Sullivan followed by Alastair Maurice Sullivan and Robyn Margaret Bridget Sullivan.
