William Shelley

By June 1816, Mary Shelley had a child. (AUDIO: The Witch from the Well)

Behind the scenes
In the real world, Mary Shelley had several children by Percy Shelley, but only one survived past infancy: At the time Mary met the Eighth Doctor, William Shelley would have been her only child, born five months prior. William died three years later in Rome (on 7 June 1819), of either malaria, cholera or typhus.
 * Clara, born in February 1815, survived only eight days.
 * William, born in January 1816, lived for 3.5 years, to June 1819.
 * Clara Everina, born in September 1817, survived 1 year, to September 1818.
 * lived to the age of 70, but he was born in November 1819.