Jackie attended Hartfield primary school in the nearby town of Dumbarton, and moved to Dumbarton Academy at the age of 12. He experienced learning difficulties owing to undiagnosed dyslexia, and due to the condition not being understood or even widely known at the time, he was regularly berated and humiliated by teachers and peers alike for being "dumb" and "thick". Stewart was unable to continue his secondary education past the age of 16, and began working in his father's garage as an apprentice mechanic. He was not actually diagnosed with dyslexia until 1980, when his oldest son Mark was diagnosed with the condition. On learning that dyslexia can be genetically passed on, and seeing very similar symptoms with his son that he had experienced himself as a child, Stewart asked if he could be tested, and was diagnosed with the disorder, by which time he was 41 years old. He has said: "When you've got dyslexia and you find something you're good at, you put more into it than anyone else; you can't think the way of the clever folk, so you're always thinking out of the box."
