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

3. Norbury

Later in the same scene, Sherlock asks Mrs Hudson to do something for him. "If you ever think I'm becoming a bit full of myself, cocky or over-confident, would you just say the word 'Norbury' to me?"

This is an update of a moment from The Adventure of the Yellow Face. When Sherlock misses the real solution to a case, he says this to Watson:

"If it should ever strike you that I am getting a little overconfident in my powers, or giving less pains to a case than it deserves, kindly whisper 'Norbury' in my ear, and I shall be infinitely obliged to you."

In the original story, Norbury is the setting of the murder, whereas in The Six Thatcher it refers to the name of the murderer - Vivian Norbury.