Dr Guy's research interests include Early Modern British History (emphasis on politics, religion, art and political culture) and related aspects of Medieval History. 

He was also pleased to announce that his 2004 biography of Mary Queen of Scots is now a major film. Dr John Guy's biography My Heart is My Own: The Life of Mary Queen of Scots was adapted as a feature film with Saoirse Ronan as Mary and Margot Robbie as Queen Elizabeth.