BBC series Ludwig stars David Micthell and Yorkshire names like Beverley's Anna Maxwell Martin, Leeds's Ralph Ineson and Halifax’s Stevie Binns

When James mysteriously vanishes without a trace, his wife Lucy, played by Motherland and Line Of Duty’s Anna Maxwell Martin – from Beverley in East Yorkshire – recruits John to assume his identity, first to sneak into his workplace and collect some notebooks she thinks will hold the clues to his disappearance.

James’s are big shoes to fill for John, not least when he gets roped into grisly crime scenes as he poses as a detective, but if anyone can crack the code to James’s disappearance, it’s Ludwig with his penchant for puzzles.

How does the twin dynamic at the heart of the story bring drama and laughs?

Mitchell, 50, says: “Well, the thing is that having a brother who’s different from you, who disappears, and you have to come out of your comfort zone to save, that is a strong dramatic idea.

"Making them an identical twin is the added coincidence that gives it its comic twist, because there is no way that without the fact that John looks identical to James, that he would ever get away with spending a day in a police station. Because he is not one of nature’s confidence tricksters! He doesn’t have that power to mirror and assimilate that some people have, so he just is completely thrown by it, and looks completely thrown by it!

“But also he looks identical to the person he’s impersonating. That’s his sort of superpower in this context. So he really, despite the extent to which he fails, certainly initially, to seem like he belongs there, he gets away with it because he just looks like the guy that does belong there. So they just assume it’s that guy, who’s going through a bit of a weird day.”

What were you first impressions of John as a character?

“My job involves a lot of showing off, and so I’m not – whatever I might sometimes feel – fundamentally introverted or shy, but sometimes I feel like I am introverted and shy.

“I think a lot of people who do performing as a job do, and then they sometimes claim to actually be introverted. And you sort of go: ‘Yeah, but there was that time at the Royal Albert Hall where you were in the middle – how did that happen? Because nobody made you!’

"Part of me can understand it’s nice, your own company is the safest.”

The show also stars Leeds actor Ralph Ineson as Chief Constable Ziegler, and in one episode Halifax’s Stevie Binns – who got her first role last year in Shane Meadows’ The Gallows Pole – as Carla.

Ludwig starts on BBC One and iPlayer on Wednesday, September 25 at 9pm.