It was announced in August that the Silk star has been cast as a “marvellously disgusting” character called Captain Hatch.

Whithouse told SFX: “[Phil Davis is] in all six [episodes]. I can’t tell you how happy I was when we got Phil. I was writing the first draft of episode six, which is a colossal episode for the character, and I was struggling to find the character’s voice; something about it wasn’t clicking. Then I thought, ‘Oh, y’know who’d be brilliant for this part? Phil Davis.’ Suddenly, writing that character became infinitely easier. Then we thought: ‘Let’s put an offer in… chances are he’ll say no.’ Much to our shock and delight, he accepted it. And he’s just brilliant – he’s so gloriously horrible in the role!”

Asked whether Captain Hatch will be the ‘big bad’ in Series 5, the writer hinted: “Yes… and it’s more complicated than that.”

Whithouse also revealed that, following the explosive exit of Mark Gatiss’s Mr Snow, leader of the Old Ones, in Series 4’s finale, the show will be introducing a new threat: “Yeah, we’re moving on to pastures new. In episode one there’s a scene that puts a full stop on the Old Ones, and we move on to much bigger and greater threats.”

Filming on Series 5 is currently underway in Wales and the six new episodes are expected to air on BBC Three early next year.

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Watch the Series 4 trailer…