The latest Sherlock episode, The Lying Detective, brought a new twist to the ongoing storyline. It is revealed that Sherlock and Mycroft have a sister, Eurus Holmes. And that in some way, she might be in league with Jim Moriarty. But eagle-eyed fans of the series, and those familiar with the wider Sherlock Holmes universe, might have spotted the clues early on.
The last few episodes of BBC’s Sherlock prior to The Lying Detective have been hinting at the possibility that Sherlock and Mycroft will be joined by a sibling in Series 4. In the last episode of Series 3, His Last Vow, Mycroft and Sir Edwin have the following exchange:
SIR EDWIN: If this is some expression of familial sentiment …
MYCROFT: Don’t be absurd. I am not given to outbursts of brotherly compassion. You know what happened to the other one.
The statement confirms the existence of a third Holmes sibling in Sherlock, unseen up until this point. In the first two episodes of Series 4, The Six Thatchers and The Lying Detective, a reference is made to “Sherrinford.” Mycroft tries to call Sherrinford in The Six Thatchers, and there is a note in his diary to call Sherrinford at 2pm in The Lying Detective. Fans of the Sherlock Holmes mythos will know that “Sherrinford” is the name of a proposed elder Holmes brother.
But the idea that Sherlock and Mycroft have another sibling is not a new one. While no such character exists in the Conan Doyle canon, several works published by other authors long after Sir Arthur Conan Doyle‘s death have featured members of an extended Holmes family.
The name, “Sherrinford Holmes,” originated from Sir Arthur Conan Doyle, even if the character did not. While he was planning the first of his Sherlock Holmes stories, “Sherrinford” was one of the names he considered giving to his consulting detective before settling on “Sherlock.” It was not until 1962, with the publication of William S. Baring-Gould’s fictional biography, Sherlock Holmes of Baker Street: A life of the world’s first consulting detective, that Sherrinford would enter the wider Holmes mythos.
In Baring-Gould’s work, Sherrinford was described as the elder brother of Sherlock and Mycroft. Baring-Gould determined that as Conan Doyle had stated that the Holmes family were country squires, there must be an elder brother who inherited and worked the estate. If Mycroft were the eldest brother, he reasoned, then the responsibility would fall to him and he would not be involved in government service. Sherlock, as the youngest brother, would also not stand to inherit the estate. Therefore, Holmes had to have a second elder brother, one who was above Mycroft to allow both Holmes brothers to play the roles they do.
Sherrinford (using an alternate spelling of Sherringford) also appeared with his brothers in Andy Lane‘s novel All-Consuming Fire, which is part of the Virgin New Adventures Doctor Who series. Sherrinford was also involved in a Call of Cthulu roleplaying game adventure, The Yorkshire Murders. He was the suspect in a murder, and Sherlock had to prove his innocence.
Eurus is not even the first time that a sister has been introduced into the Holmes clan. In 2006, author Nancy Springer wrote a series of young adult books focusing on the adventures of Holmes’ fourteen-year old sister, Enola. When her mother disappears on her fourteenth birthday, Enola’s older brothers conclude that she voluntarily left the family. However, Enola finds clues that her mother, a suffragist, instead escaped the confines of Victorian society to live with the Romani people. The brothers planned to send Enola to boarding school to further her education and learn how to be a “proper” lady.
Enola, who is a rebellious teen by the standards of Victorian society in that she likes to wear trousers and ride bikes, instead flees to London. Over the course of six books, she solves several missing persons cases and stays one step ahead of her brothers’ attempts to find her. Enola crosses paths with several characters from the Conan Doyle canon, including notably rescuing Dr. John Watson from an insane asylum. Eventually, she earns the respect of her brothers due to her work, and reconciles with them.