It is John’s habit to pull the door closed by the knocker, making it hang to the left. But notice that Sherlock’s practice is not to adjust the knocker to the left, but to the right. He’s annoyed to see that Mycroft has straightened it. To Sherlock’s mind, it should hang to the right if he is at home with John, or to the left, if John is out.
These little tiny details are what take this show to some next level shit.
JW: …So why did you want me to wear my uniform again?
SH: *slightly distracted* .. well, explaining it would take too long, John. It’s for a case, obviously!
Entry for #letsdrawsherlock: Alternative Fashion Styles!
(John wearing a uniform similar to Major James Sholto’s)