Doctor Who’s Alex Kingston and Lindsay Duncan cast in Sky One’s A Discovery of Witches

The series is produced by Bad Wolf productions, the company set up by former Doctor Who producer Julie Gardner and ex-BBC drama commissioner Jane Tranter, and shot at the new Bad Wolf Studios in Cardiff.

And now we can officially announce that Kingston (best known for her roles as River Song in Doctor Who and Dr Elizabeth Corday in ER) will play central character Sarah Bishop in the drama, the aunt of series lead Diana and a “powerful witch and fierce protector of her family” known for her plain-speaking.

“I’m thrilled to be working again with Jane Tranter and Julie Gardner,” Kingston told RadioTimes.com.

“They brought me into Doctor Who and introduced me to Cardiff! And I am back again... A home from home, with a terrific cast and crew.”

Meanwhile Duncan (who played Adelaide Brooke in Doctor Who and Lady Smallwood in Sherlock) will portray Ysabeau de Clermont, the vampire mother of Goode’s Matthew Clairmont who has a “powerful dislike of witches”.

“It was only a matter of time before I was asked to play a vampire. At last!" Duncan said.

"I’m thrilled to be involved in the series. I know Bad Wolf will make something really special.”

Other new cast added to the roster include The Blacklist’s Valarie Pettiford (playing Emily “Em” Mather, the partner of Kingston’s Sarah) and Sherlock's Tanya Moodie as Agatha Wilson, one of the daemon members of the Congregation (both pictured above).

"I’m overjoyed to be part of such a fine cast," Moodie said. "Agatha is a beautifully layered character to be playing. I love the book and look forward to sharing this amazing project with its many fans."

The four actors will join already-announced cast members including Goode, Palmer, Sherlock's Louise Brealey, Fresh Meat's Greg McHugh, Game of Thrones' Owen Teale, Atlantis' Aiysha Hart, Strike: The Cuckoo's Calling's Elarica Johnson and Waking the Dead's Trevor Eve, with filming currently underway in Wales.

An official series description can be read below.

Brilliant historian Diana Bishop (Teresa Palmer, Hacksaw Ridge) is a witch denying her own heritage. But when she unexpectedly calls up an ancient, bewitched manuscript from Oxford’s Bodleian library, one that was thought by the creatures to be lost and could answer the mysteries of their existence, she finds herself thrown into the heart of a dangerous mystery – and into the path of the enigmatic geneticist and vampire Matthew Clairmont. (Matthew Goode, Downton Abbey)

Matthew is driven to solve the looming threat of the creatures’ decline and extinction, but their unlikely alliance to find the book before it falls into the wrong hands – and their deepening relationship – threatens to violate age-old taboos and shake the fragile peace that exists between the species.

A Discovery of Witches will air on Sky One in 2018