Cast as on-screen lovers Young Bess (Queen Elizabeth I) and Sir Thomas Seymour, in real life Jean Simmons and Stewart Granger were married to each other when this movie was filmed. Granger (né James Stewart) and Simmons met in 1946 while working on the picture Caesar and Cleopatra (1945). They would meet again over a year later, with Simmons now a grown up 18. The relationship soon turned to romance, and the couple appeared in a film that reflected their own situation. In Adam and Evalyn (1949), Granger plays a man in love with a younger woman. Later, after divorcing his first wife, Granger and Jean married on December 20, 1950. He was 27. The bride was 21. They also appeared together in Footsteps in the Fog (1955).
Simmons said of her scenes with Granger in the film, "I feel more self-conscious about playing love scenes with him now, than I did before we were man and wife." But the chemistry flourished on screen.
Deborah Kerr (Catherine Parr) and Rex Thompson (young Prince Edward) played mother and son in The King and I (1956).
Vivien Leigh had a life-long movie contract with Metro Goldwyn Mayer since making A Yank at Oxford (1938) where, as she was sent scripts for first refusal and this movie was one of them. Leigh turned down the role of Bess due to acting obligations in her home country of England.
The second time that actor Charles Laughton played Henry VIII on film. The first was The Private Life of Henry VIII (1933) for which he won an Oscar as Best Actor twenty years earlier.