Doctor Who boss Russell T Davies explains why scenes with Kate and the Doctor are "very hard" to write

Ahead of tonight's The War Between the Land and the Sea finale, titled The End of the War, creator Russell T Davies and his co-writer Pete McTighe sat down with BBC digital series The Whoniverse Show – which you can watch on YouTube – to talk about the Doctor Who spin-off.

While discussing the origins of the series and previewing the finale, which Davies described as "carnage", conversation naturally turned to Jemma Redgrave's Kate Lethbridge-Stewart, head of UNIT, who has been a Doctor Who mainstay since her introduction in 2012.

"It's amazing to see Kate's character built out a bit more because she's been in Doctor Who for quite a while now," said presenter Christel Dee.

"It's lovely to see her really be pushed to the limits," she added, before asking the pair to talk us through her journey to date.

Davies was full of praise for Redgrave herself, saying that he promoted her to head of UNIT because she's so "wonderful" and he was always "determined to give her more to do". But he also said that was easier said than done.

"It's very hard to give Kate more to do when the Doctor's there, because he knows everything and does everything," he explained. "So it was a great opportunity for her to spread her wings in this, and off she goes."

McTighe continued: "I did a little bit of that in [season 15, episode 4's] Lucky Day, just pushing her into slightly darker territory... when she's kind of confronted with all that terrible stuff that's happening, knowing where we were going in this and what we were kind of setting up in this.

"But it's just great to be able to invest so much more time in that character... and watch that journey. It's an amazing journey that goes right to the very end of the series."

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"And the very end of her wits," chuckled Davies, as he referenced the scene in episode 5 when she meets with her psychiatrist.

"She shows sides to her you've never seen before, and she's ferocious. I love her," he added.

Davies also revealed that the romance between Kate and Colonel Christopher Ibrahim, which was teased in Doctor Who, was always going to be developed further.

"It's a lovely relationship that's been borne very naturally and allows us to explore Kate more, and also allows us to explore Christopher, who's been very noble and dutiful and doing his job – but now he's got an inner life... so interesting things to come with those."

While details about what you can expect in the finale have been kept firmly under wraps, Redgrave has teased that there could be some serious jeopardy in store for Kate.

Redgrave told RadioTimes.com exclusively: "If she survives this series, I don't know where she can go next…

"But I've had a most extraordinary time and journey with this character and through different series of Doctor Who and now through this series. And every time I get the call, it feels like another gift. Long may it last."

The War Between the Land and the Sea finale airs on Sunday 21st December at 8:05pm on BBC One and BBC iPlayer.

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