Mary Watson death scenes were fun - Sherlock star Amanda Abbington
Sherlock actress Amanda Abbington has said filming the scenes of the death of her character were "sensitively handled" - and even "really fun".
The first episode of the fourth series, which returned on New Year's Day, sees her character Mary Watson being shot dead as she jumps in front of a bullet intended for the lead character, Sherlock Holmes (played by Benedict Cumberbatch).
Abbington, 42, and Sherlock star Martin Freeman, 45, who plays her on-screen husband John in the popular BBC One series, recently made headlines with news that their 16-year relationship off screen has reportedly ended.
The new series sees their characters introduce their baby daughter, Rosamund Mary Watson, to fans.
Talking at a screening of the episode held in central London a few weeks before it aired, Abbington said filming the death scenes were "really fun".
She said: "It was good, we took a day and a half, it was sensitively handled but it was good fun because I worked with these guys (Benedict and Martin) and these guys are brilliant.
"It's always nice when you get something like that in the script, and it says you get shot and you have to say all of these last things, it's a dream for an actor because you can just kind of just completely self-indulge nad go to town with it and I think I did.
The popular series, which is written and created by Doctor Who's Steven Moffat and Mark Gatiss, is inspired by the original works of Scottish author Sir Arthur Conan Doyle.
Gatiss, who also stars in the series as Sherlock's brother, Mycroft, explained: "We did an early road map, it's a strange thing but actually in the original stories it's not actually said she's died, it is heavily inferred, but it could have been a messy break up.
"But we've obviously been very true to Doyle and also very untrue, so we didn't necessarily have to do this (kill off the character), but it just felt the right place to do it."
Moffat, 55, said the difficulty was that as the character of Mary has been "dead for a hundred years" it is difficult to "surprise people in those circumstances".
"So the only thing we could do was to do it earlier than people thought so it would happen as wrenchingly and as horrifically as such things happen in real life, so that's what we went for," he said.
As characters, Sherlock and Mary share a complex history, which has seen in a previous episode Mary attempt to assassinate Sherlock.
The events leading up to her death in the first episode also offer a glimpse into Mary's past as a secret assassin.
Moffat said: "Obviously we had the thing hanging over us, Mary and Sherlock were very close but there was that moment of froideur when she shot him in His Last Vow (a previous episode), so it was nice to reverse that and have her save his life."
Cumberbatch said filming the scenes were emotional, adding that the cast "get the hit the audience gets hopefully when they watch it, when we first read it, so that was always going to be a moment in the schedule and it was a big moment ."
He added: "This incredibly important part of what Sherlock is, is no more in the most violent way imaginable and a mother as well as a wife and dear friend (is gone), and you discover more about her just as you lose her as well.
It's a great bit of tipping someone over the edge of a cliff ... so it was a very upsetting scene to film."
Freeman appeared to reference his off-screen relationship with Abbington when asked about filming the death of Mary.
He said: "It's difficult because, you're kind of, I am, always on the verge of acting badly and so you have to work up to a point where you could really get caught out acting badly, especially when it's your wife on telly and who we are in real life, so you kind of have to do it justice obviously, but it's very easy to overdo it, so it's a careful line to walk."
Series four is comprised of three feature length episodes and will give viewers a glimpse of a different side to the usually arrogant Sherlock they know.
Referencing a previous comment by Moffat, who joked that Sherlock would be "less of a dick" in the current series, Cumberbatch said: "Yes, I think he's slightly less of a dick."
"He takes himself off to therapy at the end of the episode, he's becoming slightly more, in a very clear way responsible for his actions, but I think he understands it is a slow process that began the first very instant when he met John, when that immediate, missing part of the jigsaw, when they collide, when that partnership in crime began, that has been a humanising element all the way through and I think he's very much now becoming more of a human being."