The War Between the Land and the Sea stars break down "risky" romance reveal in new Doctor Who spin-off

*Warning: Spoilers ahead for The War Between the Land and the Sea episodes 1-2.*

Already, Doctor Who spin-off The War Between the Land and the Sea has offered up multiple twists and turns, including the reveal of a relationship that has been a long time coming.

After some chemistry-filled moments in Doctor Who season 15, the first episodes of The War Between confirm Kate Stewart (Jemma Redgrave) and Colonel Ibrahim's (Alexander Devrient) relationship and give a glimpse into the pair's home life together – with all of its complications.

Speaking exclusively to RadioTimes.com, Redgrave gave her insight into that reveal, explaining that the two characters feel very differently about the relationship.

"I think the conflict for her is the thing that struck me about the relationship…. I don't believe that she thinks [the relationship] has a future because of the age difference, because of the power imbalance – but mainly for the age difference," she pointed out.

"What we discussed was how differently they both felt about it and that being interesting. It's there in the script, it's there in the episodes that Pete [McTighe] and Russell [T Davies] wrote, the deep differences between the way they feel about this relationship and what the future is for both of them.

"I think there's a very key line in episode 2 about [Colonel Ibrahim's] father. [Kate] says ‘He sounds very wise,’ and he says, ‘You should meet him.’ And I think in her mind, that seems impossible. But also she has no time at this minute, there's no time to talk about it. There's no time, really, for their relationship. And I think that's the other difficulty, is that she's so driven, and her work is so important. It's the most important thing that runs through her life."

Meanwhile, Devrient added: "There were a lot of little moments that were placed throughout the seasons [of Doctor Who]. And to be honest with you, we weren't even sure, me and Jemma, whether this was going to go any further or not. Initially, we held back a little bit.

"Obviously, there is the hierarchy element, when you work in a sort of context that we work in within UNIT, that's quite important. There's an important age gap. There are various different factors that meant that this is quite a tricky and risky potential relationship.

"But, in the end, I think also with with what Russell wrote and how he wrote it, we just thought, 'Okay, we're going to go for it.' These two, there is something behind that element of stoicism and respect and loyalty and discipline, something really pure and beautiful, a connection that they can't really fight against. Let's just go with that and explore what that looks like when you're in the midst of yet another catastrophe."

As Devrient points out, the relationship is revealed as humanity is faced with a crisis, with classic Who monster the Sea Devils (also known as Homo Aqua in the spin-off), emerge from the oceans and reveal their presence to the entire world.

Their leader, Salt (played by Gugu Mbatha-Raw) appoints Russell Tovey's Barclay as ambassador for humanity (despite his lacking experience), and the pair are charged with preventing a world-ending war on Earth.

As for what's next?

"[Humanity] is going to try everything," Devrient teased. "And I think that's what's really interesting is, when your backs are against the wall, you see how different players react, and what the points of interest are for each of these players.

"Maybe that works perfectly in unison to be one voice, or, potentially, there is conflict there as well – and what does that conflict look like? It's tense. It's not a nice environment to be in."

He added: "There are still lots of thrills, and lots of twists and turns to come, epic stunts, massive production design. They've really sort of pulled out all the stops for this one, and it looks great."

The War Between the Land and the Sea continues on BBC One and BBC iPlayer on 14th December.

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