74. The original Doyle character of Charles Augustus Milverton was based on a real blackmailer, Charles Augustus Howell, a Victorian art dealer who was murdered in mysterious circumstances.

75. Early on in the script was the idea that Mary would be taking violin lessons from Sherlock, which he enjoyed giving, only for her arrive at a different time to usual one week and present her case to him as a client.

76. Magnussen’s office building is an amalgamation of three different London locations including the Tower 42 skyscraper where his office scenes were filmed.

77. The idea that close contact with a mobile phone could corrupt a key card, discussed by Sherlock in the lobby of Magnussen’s office building, came to Moffat while on the Sherlock TCA press tour in the US, when he was repeatedly warned not to keep his hotel key card near his phone in case corruption occurred.

78. The people playing the security men who freeze frame while Sherlock is explaining his potential routes to Magnussen’s office to John were street performers from Covent Garden cast because they could convincingly hold a position as if paused for a long time.

79. When the word “liar” flashes up around Mary in this scene, originally the word was spelled incorrectly as “lair.”

80. The ‘mind palace’ first appeared in the Gatiss-written episode The Hounds Of Baskerville, inspired by its use in the Thomas Harris novel Hannibal, mostly as a way to avoid Sherlock having to conveniently say ‘hang on, I’ve just remembered something’ which helps him to solve the case.

81. Sue Vertue and Steven Moffat’s son Louis (credited as Louis Oliver) plays the young Sherlock Holmes in the mind palace scene, and later, at Appledore. He auditioned for the role, for which he had to wear different coloured contact lenses and dye his hair.

82. In the scene where Sherlock falls back slowly, the orchid plant is simply pulled along the shelf using fishing line, the whole set did not rotate, as some thought it had.

83. The Holmes boys’ childhood dog Redbeard was named, according to Gatiss, “after Sherlock’s pirate fixation as a child,” in reference to Mycroft’s A Scandal In Belgravia line “initially, he wanted to be a pirate.”

84. Moffat used the same rhyme Moriarty says in the padded cell: “It’s raining, it’s pouring, Sherlock is boring” in his 2007 TV series Jekyll, in which Mr Hyde leaves a message on Mr Jackman’s Dictaphone saying “It’s raining, it’s pouring, Jackman is boring.” He was unaware of having re-used the line.

85. The production team has had several summer coats made for Sherlock as an alternative to his Belstaff winter coat, but they are always rejected because, in the words of Steven Moffat, “He has to wear the coat. He always wears the coat”.

86. A now deleted scene (which features as one of the extras in the special edition DVDs) was filmed in which Magnussen goes to visit Sherlock in the hospital and licks his hand, calling it a musician’s hand, and ‘a woman’s hand’. Moffat denies any deliberate reference to Tom Baker’s famous line as Captain Redbeard Rum in the Blackadder II episode “Potato,” when he tells Edmund Blackadder, “You have a woman’s hands!”.

87. Originally, the script for the scene in which Janine visits Sherlock in hospital had them making friends at the end and making a deal to get together if neither had found anyone else by the age of sixty. In that script, Sherlock told Janine to “keep the bee hives” at the cottage in Sussex she’s buying with her tabloid kiss-and-tell money (a reference to Doyle’s character’s literary retirement home), but it was cut because it was felt that it got Sherlock off the hook too easily for his awful behaviour to Janine.

88. The corridor in Sherlock’s mind palace in which Mary stands wearing her fur with the word “liar” swimming around her is the same one that Watson ran down to save Sherlock in A Study In Pink.

89. Another hospital scene was cut from this part of the episode in which a doctor complained that someone had taken all the ward’s morphine and was told “Yeah, he does that,” in reference to Sherlock.

90. Moffat regrets cutting some lines in the scene where Watson notices the perfume bottle that make it clear that Sherlock has been back to the flat. The original script referenced some missing food. “By cutting that, it’s not immediately impactful that he’s left the perfume bottle, so I regret that, I wish we’d kept that.”

91. Gatiss discovered the real-life secret of the fake facades at 23 and 24 Leinster Gardens (a plot point in His Last Vow) while researching the London underground for The Empty Hearse and subsequently tried to fit it in to both that episode and The Sign Of Three, finally making room for it in His Last Vow. Apparently, local pizza delivery companies commonly send employees to the address, which is merely a five-foot-deep facade, on their first day as a prank.

92. A couple of lines between Mary and Sherlock were cut from the scene after he appears behind her in the Leinster Gardens corridor. Originally he said, “You saved my life” and she replied “I nearly killed you” and he says “And you didn’t hit the middle of the coin. Nobody’s perfect.” Moffat wishes he’d kept those lines in.

93. Gatiss says “my favourite bit, in the midst of this emotional trauma, is that John is still mostly concerned about sorting his hair out” in reference to Freeman smoothing down his mussed hair after pretending to be Sherlock in silhouette.

94. Benedict Cumberbatch’s dad, Timothy Carlton, insisted on wearing the garish red bow tie on the Christmas Day scenes because he says he wears bowties and musical socks at Christmas in real life to embarrass him.

95. Mary’s ‘real’ initials on the USB stick, A.G.R.A, are a reference to the great Agra treasure which is the character’s inheritance in the Doyle story which introduces the character of Mary Morstan, The Sign Of Four.

96. The slow-motion fall and Mary hitting Magnussen scene was filmed using a Phantom camera. A special camera rig was also designed that had a camera attached to a bicycle wheel mounted on the ceiling so it would pivot around the set.

97. Amanda Abbington didn’t know what Mary Morstan’s backstory was going to be when she was filming The Empty Hearse and His Last Vow. “Amanda certainly wasn’t imbuing it with ‘spirit of assassin’” says Freeman. “I’m playing it all very innocently. I would have played her differently, had I known her backstory”, says Abbington.

98. Sherlock’s fall backwards when Mary shoots him was achieved using a custom-built rig that was moulded to Cumberbatch’s body contours and operated by a manual lever outside the set. The moment was inspired by director Paul McGuigan filming of Sherlock falling backwards, when drugged by Irene Adler, onto his bed in A Scandal In Belgravia.

99. In the scene where Mary shoots Sherlock, His Last Vow director Nick Hurran asked for there to be a delay between the bullet-hole appearing and the blood beginning to flow, so the audience could momentarily believe he wasn’t injured, to make it more dramatic when they realise he is.

100. Cumberbatch and Gatiss were smoking herbal cigarettes in the Christmas Day scene in the garden, until Cumberbatch requested real ones.

101. The line from Mycroft to Sherlock that “your loss would break my heart” was heavily debated, but left in on the understanding that Mycroft had been drugged by that point, explaining his emotional candour.

102. Mark Gatiss gave Steven Moffat a Holmes-style magnifying glass for his fiftieth birthday.

103. Magnussen’s henchman with the long white ponytail was one of the card players in Le Chiffre’s game in 2006 Bond film Casino Royale, which, coincidentally, starred Lars Mikkelsen’s brother, Mads.

104. Moffat originally used news magnate Magnussen’s line “I don’t have to prove it, I just have to print it”, in an episode of Press Gang, his 1989 – 1993 CITV series about a school newspaper.

105. Sue Vertue directed the moment of Mycroft saying “Sherlock, what have you done?” in the helicopter (which was actually a plane).

106. Benedict Cumberbatch requested various ways of killing Magnussen, at one point asking if he could twist his neck. “He’d gone a bit Khan” says Moffat.

107. Mycroft’s reference to the “blunt instrument” is a direct quote from one of the Bond continuation books written by John Gardner.

108. The plane Sherlock is taken away in was lent to the production by its owner, Bruce Dickinson from Iron Maiden.

109. The name William Sherlock Scott Holmes was taken from the fictional 1962 biography of Holmes’ life, Sherlock Holmes of Baker Street: A Life Of The World’s First Consulting Detective, written by William S Baring-Gould.

110. Sherlock’s “the East wind takes us all in the end” line is taken from Doyle’s His Last Bow, from a conversation between Sherlock and Watson on a balcony, which is canonically, the last time the pair ever speak.

111. Sherlock could go on indefinitely, according to its creators: “The idea, if we could of finding Martin and Benedict in these chairs aged fifty – sort of the age Holmes and Watson are usually portrayed – is sensational. It would be lovely to feel we could do that.”

The Sherlock series 3 special edition box-set is available now on DVD and Blu-Ray, and available to buy from the BBC Shop, here.