Agnes Wickfield is most likely based on Charles Dickens’ deceased sister-in-law, Mary Hogarth.
Mary moved into the home of Charles and Catherine Dickens when they were still newlyweds.
In 1837, Mary, who was still in her girlhood, suffered a sudden illness and died in the arms of her brother-in-law. Her death had a deep impact on Dickens and caused him to miss a deadline for the first time in his writing career. Charles and Catherine named their first born daughter Mary “Mamie” Angela Dickens.
In death, Mary became to Charles Dickens an embodiment of female goodness and she inspired many of his angelic female characters, such as Little Nell in The Old Curiosity Shop (1840-1841) and Mary Graham in Martin Chuzzlewit (1843-1844).
Mary’s death is thought to have been depicted in The Old Curiosity Shop in the demise of Little Nell.