Stewart grew up in a poor household with domestic violence from his father, an experience which later influenced his political and ideological beliefs. He spent much of his childhood in Jarrow. Stewart's father served with the King's Own Yorkshire Light Infantry and was regimental sergeant major of the 2nd Battalion, Parachute Regiment during the Second World War, having previously worked as a general labourer and as a postman. As a result of his wartime experience during the Dunkirk evacuation, his father suffered from what was then known as combat fatigue (related to what is now known as post-traumatic stress disorder). In a 2008 interview, Stewart said, "My father was a very potent individual, a very powerful man, who got what he wanted. It was said that when he strode onto the parade ground, birds stopped singing. It was many, many years before I realised how my father inserted himself into my work. I've grown a moustache for Macbeth. My father didn't have one, but when I looked in the mirror just before I went on stage I saw my father's face staring straight back at me. "