Mary Seymour was the only child of Catherine Parr and Thomas Seymour, born in August 1548. Her mother died soon after childbirth, and her father was executed for treason the following year. The orphaned infant was placed in the care of Catherine Willoughby, Duchess of Suffolk, who complained about the expense of maintaining her household.
Records then fall silent, and Mary probably died in early childhood, although no certain date or burial is known. Mary appears at the end of novels about Catherine Parr, including Elizabeth Fremantle’s Queen’s Gambit and Alison Weir’s Katharine Parr, The Sixth Wife. Her brief life gives a sombre conclusion to the ambitions and scandals surrounding her parents.
In Alison Weir’s The Queen’s Child, After Katharine Parr’s death, the infant Mary Seymour becomes a problem for relatives who lack the money or political will to support her. In Sandra Byrd’s The Secret Keeper, The story continues through Henry’s death, Katherine’s marriage to Thomas Seymour and the dangerous household that includes Princess Elizabeth.