What is the name of John and Mary's daughter in The Six Thatchers?

John and Mary Watson name their daughter Rosamund Mary in “The Six Thatchers.”

Rosamund Mary is born during the episode, adding a joyful family milestone before the story turns toward Mary’s dangerous past. The baby’s first name is commonly shortened to Rosie in later Sherlock discussions, but “Rosamund Mary” is the full name given in the episode’s story.

The name connects her to both sides of the family. Rosamund is the formal name used for John and Mary’s daughter, while Mary is her mother’s name. Her birth takes place against the backdrop of Sherlock’s return from exile and his efforts to solve a series of attacks involving Margaret Thatcher busts.

A frequent mix-up is confusing Rosamund Mary with characters or code names from the wider plot. AGRA refers to Mary’s former intelligence team, and Sherrinford is connected to Mycroft’s later investigation; neither is the child’s name. The episode was written by Mark Gatiss and Steven Moffat and directed by Rachel Talalay.