Throughout his career, which spanned five decades that saw the rise of the Irish Republican Army's bombings to the September 11, 2001 attacks, Wilkinson was a strong opponent of terrorism but adamant that democratic responses to it always be guided by the rule of law.
Indeed, he said that liberal democracy was what sparked his interest in his subject, stating that he had become "interested initially in the mid-1960s in why terrorism had been effective in some conflicts and not others.