Mezue ahịrịokwu na-esonụ: Amụrụ na Ayrshire, Duncan gara Ardrossan Academy na Ardrossan, North Ayrshire ma gụrụ akwụkwọ na Mahadum Birmingham ebe ọ nwetara BCom na 1985. O mechara rụọ ọrụ dị ka onye na-ahụ maka azụmahịa na nkwukọrịta maka Mackays Stores Ltd site na 1985 ruo 1988 na mgbakwunye na ị na-agba ahịa azụmaahịa ezinụlọ - John Duncan & Son site na 1988 ruo 2000. Na Septemba 1997, ọ pụtara dị ka onye na-ege ntị n'oge arụmụka Scottish Television banyere
referendum, ma kwuo okwu megide nguzobe nke nzuko omeiwu nke Scotland. Duncan mechara tinye ọnụ n'ọchịchị nke ọ na-emegide na mbụ.