Would you describe Ludwig as a series about solving murders or solving relationships?

Both, I think the heart of the show is Lucy and John’s relationship, with sleuthing as an accidental bonus.

How would you describe Lucy and John’s relationship?

Lucy and John are light and shade. Their relationship is very sweet and nuanced, written really well by Mark Brotherhood. Lucy is completely understanding and accepting of John, their care for each other is unconditional.

What do you admire about Lucy?

What I like about her is that she is indomitable. She is always positive, like a puppy, despite what has happened to her. John is the Eeyore of the piece.

What particularly appealed to you about working with David Mitchell?

I suspected he was a good egg. I didn’t know for sure. He might have turned out to be a bad egg, but it transpires that he is 100% good egg. David is great, we had a really nice time.

How good are you at solving TV murder mysteries?

My mum and I love them. Our favourites are Silent Witness, Vera, McDonald and Dodds. Mother and I really like a murder mystery to be wrapped up in one episode, which is the case with Ludwig. I’m a bit of an instant gratification person.

The script describes Lucy as someone who never does as she’s told. How about you?

In my job I have to do what I’m told. If actors didn’t do what they were told we would never make our day. We would be constantly behind.

John once gave Lucy a four-leaf clover as a keepsake. Would you do anything like that?

No, I don’t hold onto anything. I am constantly down the tip. That four-leaf clover would have been straight in the tip.

What’s your favourite way of passing the time between set-ups?

Eating biscuits and nattering.

How would you describe Lucy’s look?

I’ve tried to get some quirky stuff in. I wanted some weird applique jumpers and stuff like that. I just wanted her to be a little bit off. I think we’ve achieved that.

You’ve worked with the Ludwig hair and makeup team on other shows like Motherland. What makes them so good?

I first worked with Nessa White and Lesley Altringham 11 years ago on Alpha Papa, the Alan Partridge film. Then we went all the way through on Motherland. Nessa is the head honcho, she is amazing and very clever. She has helped me a lot on other projects where there has been no budget. I’ve known Nessa for years, but Lesley is my support dog. Actually, I am more of Lesley’s support dog. The makeup truck is the heart of the show without a doubt. You have got to have a jolly, positive team and we definitely did on this.

David has all the lengthy crime solving speeches in Ludwig. Do you miss the marathon ones you had as DCI Patricia Carmichael in Line of Duty?

I do, and I would do it all again in a heartbeat. There is no greater gift for an actor than being given a part like that. I had worked with Vicky McClure before on a film called Mother’s Day. I told her I loved Line of Duty so much that I would be happy to make the tea in the background. When I was told Jed was offering me a part, I thought that’s what it was, making tea. It wasn’t. I love Patricia as a character. Jed Mercurio was brilliant to work with – creative but also hands-off – and Sue Tully who directed those episodes was exceptional. She knows what she wants, and you have such confidence in her. They just let me really go for it.

On Motherland there was an opportunity to improvise. Is that the case on Ludwig?

I do change the odd bit in Ludwig but not hugely. That’s only because things change when you get there and as you develop the character. There are some parts where you feel so lucky to have been afforded the opportunity and Motherland is one. I will always be grateful to Graham Linehan and Sharon Horgan for taking a chance on me when I hadn’t done any comedy before. Sharon is a powerhouse. She is an inspirational woman in the business.

Do we get to see Lucy doing any amateur sleuthing?

She does sleuth. She wanders off on her own and goes rogue.

Do you enjoy a puzzle?

I do a puzzle every morning.

If there is the opportunity, what would you like to see more of Lucy doing in future Ludwig mysteries?

I would get her out of the house and doing more sleuthing. This season we’re telling the story of Lucy being a bit green around the gills. If there was a series two I would get her out and into a bit of danger. I think she can do the danger more than John.

What other TV shows have you admired recently?

Kin on BBC iPlayer. That’s my current favourite programme. It is brilliantly conceived, brilliantly cast, brilliantly designed, created and directed. The actors are so super. I just love every single one of them. And then in the second season there is one of the best and most frightening baddies I think I have ever seen on TV. Francis Magee as Bren Kinsella. If I met him, I would be so overwhelmed. I had to phone my Irish friends to ask what he was like in real life. ‘Is he horrible?’ No, of course not, he is the sweetest man. It’s such a good show.

What makes Ludwig special?

There is a lot of heart in this show and David and I have a good relationship in it, so I am willing it on.

When John ‘Ludwig’ Taylor’s (David Mitchell) identical twin, James, disappears off the face of the earth, John takes over his brother’s identity in a quest to discover his whereabouts. John has never married, never had a family and never really ventured further than his own front door. Without a computer, mobile phone or even a television, he lives in quiet solitude, designing puzzles for a living, under the nom-de-plume of ‘Ludwig’.

However, filling the shoes of your identical twin is one thing – when your twin also happens to be a successful DCI leading Cambridge’s busy inner-city major crimes team the stakes are much higher. John may be a master of all things cryptic, but can he crack the biggest puzzle of his life?

Joining David Mitchell in the ‘case-of-the-week’ crime comedy-drama is Anna Maxwell Martin (Motherland, Line of Duty), as Lucy Betts-Taylor, John’s sister-in-law and wife of his missing brother James.

Also joining the cast are Dipo Ola (Landscapers, We Hunt Together), Gerran Howell (Catch-22, Suspicion), Izuka Hoyle (Boiling Point, Big Boys), Dylan Hughes (Malory Towers, Maternal), and Dorothy Atkinson (Mum, The Gold).

Ludwig (6×60) is a Big Talk Studios in association with That Mitchell And Webb Company production for BBC One and BBC iPlayer. It was commissioned by Jon Petrie, Director of Comedy Commissioning at the BBC. The series is written and created by Mark Brotherhood. The Executive Producers are Kenton Allen, Mark Brotherhood, Saurabh Kakkar, David Mitchell, Kathryn O’Connor and Chris Sussman, the Producer is Georgie Fallon. The Directors are Robert McKillop and Jill Robertson. The BBC Commissioning Editor is Tanya Qureshi. It is produced in association with ITV Studios, which will distribute the series internationally.

Watch Ludwig on BBC iPlayer from Wednesday 25 September, with weekly episodes from 9pm on BBC One.