John Syme Duncan Blackwood was born in 1935 in Cronberry, a community in East Ayrshire, Scotland. East Ayrshire is a council area in south-west Scotland, a region that forms part of the wider Ayrshire area.
Little is documented about his family or early years. His playing career belongs to a period in which Scottish footballers were a visible presence in English league clubs, as the squads of Accrington Stanley in the mid-1950s illustrate.
Before his English league career, Blackwood played as an inside forward for Girvan F.C. Girvan is a town in South Ayrshire, and the present-day club of that name was formed in 1947 and plays in the West of Scotland League.
Blackwood joined Accrington Stanley in 1958. He made four Football League appearances for the club during the 1958–1959 season and scored one goal. Accrington, founded in 1891, had been a Football League member since 1921, and in 1958–1959 it competed in the newly created national Third Division, finishing nineteenth. In the mid-1950s the club, under manager Walter Galbraith, often fielded an all-Scottish side.
In 1959 Blackwood moved to York City, a club founded in 1922 that had joined the Football League in 1929. York City became one of the original members of the Fourth Division when it was created in 1958. He made no league appearances for York City, and his league career ended in 1960.
