Doctor Who spin-off pushes boundaries, says Russell T Davies

A composite image. On the left, Tovey is in character as Barclay and is stood in front of a orange and red fire themed background. He is wearing a green t-shirt and is stood with his arm reaching into the other side of the image with his hand touching Mbatha-Raw's hand. On the right, Mbatha-Raw is in character as Salt, and is stood in front of a blue ocean background. She is dressed as a mystical creature. — Image caption,
The War Between the Land and the Sea stars British actors Russell Tovey and Gugu Mbatha-Raw

Eleri Griffiths

BBC Wales

9 December 2025

A new BBC Doctor Who spin-off drama takes a "tougher tone", says writer Russell T Davies.

The War Between the Land and the Sea, starring Russell Tovey, Gugu Mbatha-Raw and Jemma Redgrave, follows humanity's response to an ancient species rising from the sea and triggering a global crisis.

Davies said the story was inspired by his environmental concerns and sees its characters "pushed to the limit" without the Doctor's usual "safety net".

Produced by Bad Wolf, the five-part science fiction series launched on 7 December, featuring extensive underwater sets, and was filmed largely in Cardiff.

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writer Russell T Davies is wearing a red and blue checked shirt with a black jacket. It's a professional photograph taken on the set of Dr Who. You can see the Tardis in the background. He has dark hair and wears black glasses. He is resting one elbow on the arm of his seat and his knuckles are facing down on the other armrest. — Image caption,
The series is written by Welsh screenwriter Russell T Davies, known for It's a Sin and Doctor Who

The series follows UNIT employee Barclay, played by Tovey, whose ordinary life is upended when an ancient species rises from the sea.

UNIT is Doctor Who fictional universe's military organisation.

He becomes humanity's representative after the mysterious Salt, played by Mbatha-Raw, emerges during a Thames summit, while UNIT, led by Kate Lethbridge-Stewart, played by Redgrave, struggles to maintain order.

Davies, who is originally from Swansea, said the story had been "stewing for a long time", inspired by his home by the sea and concerns about "the state of the environment and the awful things we're doing to the sea".

He said he wanted to expand the Doctor Who universe by removing the Doctor to explore how humanity copes, resulting in a "properly entertaining thriller" of monsters, romance, chases and gunfights.

Davies also explained how research included consulting geneticists and revisiting the history of the Sea Devils and how Homo Aqua "could have branched off from mankind millions of years ago".

He stressed the series remained accessible to new viewers, while refreshing long-time fans on the "lores of what's gone before" and introducing new elements.

Tovey in character as Barclay standing on the steps outside the National Museum Cardiff. He wears a navy suit and looks distressed as rubbish is circulating him in wind. Behind him, an armed officer can be seen and a man in a suit running in distress. — Image caption,
Many familiar Welsh locations feature in the series, including the National Museum Cardiff

In Cardiff, filming locations included the Bay and Penylan areas of the city, as well as the City Arms pub in Cardiff centre, Hodge House - a Welsh government building, Cardiff City Hall and National Museum Cardiff.

Other Welsh filming locations included Merthyr Mawr, Town Bridge in Newport, the University Building and Guildhall in Swansea and Atlantic College (St Donats Castle).

Mbatha-Raw described the Cardiff sets as "really, really epic".

She said: "One of my favourite sets was under the ocean in Salt's domain.

"Everything else up until that point, Salt is out of her comfort zone in the human world and breathing human air.

"Stepping onto that set really transported you to another world."

Davies also said he was "so excited" by the sets, calling them "absolutely gorgeous".

"Our design team has done such a brilliant job," he added.

Doctor Who spin-off pushes boundaries, says Russell T Davies

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