Written by Steven Moffat, ‘His Last Vow’ will air at 8.30pm on Sunday 12 January on BBC One.

Freeman commented: “It’s particularly important you end on a fantastic third one and the third episode in the third series is stellar. Everyone’s work on it is great and it’s a Steven Moffat special which is always good, but they are all so good! I was very, very excited when I read this one – it’s one of the best scripts I’ve ever read.”

The Hobbit actor also hinted at what to expect from the episode’s villain, Charles Augustus Magnussen: “Lars Mikkelsen is fantastic, he is a brilliant villain. For those who will miss Moriarty, which is totally understandable, we have another fantastic nemesis for Sherlock and John – he does it superbly.”

The official synopsis for the finale reads: “A case of stolen letters leads Sherlock Holmes into a long conflict with Charles Augustus Magnussen, the Napoleon of blackmail, and the one man he truly hates. But how do you tackle a foe who knows the personal weakness of every person of importance in the Western world?”

> Find out all the details on Series 3 so far in our summary.

Are you looking forward to ‘His Last Vow’? Let us know below…

> Order Series 3 on DVD on Amazon.

> Buy the Series 1-2 boxset on Amazon.

Watch the Series 3 teaser trailer…