Sherlock Season 4: 20 Easter Eggs & References From The Six Thatchers

1. Put Me Through To Sherrinford

After picking his menu, Mycroft finds a post-it note with "13th" written on it hidden underneath. Immediately, he calls up someone named "Sherrinford."

The ears of Holmes fans everywhere pricked up at the mention of this name. Since Mycroft talked about "the other one" last season (a clip replayed at the start of this episode), we have known that a third Holmes brother was on the way.

For those not in the know, Sherrinford is the name of the eldest Holmes sibling. Though the character was not created by Conan Doyle (rather he was invented for a fictional biography of Holmes' life, written by William S Baring-Gould), he became part of the Holmes legend.

And it looks like he will be putting in an appearance on Sherlock very soon...