Born in Scotland, Armour grew up in Liverpool before graduating from the University of St. Andrews and the Edinburgh College of Art. After college he moved to Morocco to buy horses and later ran a stud farm in Wheathampstead, England. He later went to the Spanish Riding School in Austria to study military equitation before World War I when he commanded a remount depot in Greece. He is best known as an illustrator for Punch, Country Life, and The Graphic.