Born in Edinburgh to an artist father, Stan, and mother, Rosi, Bonnar, 56, grew up in postwar New Towns around Edinburgh and Glasgow. He worked for Edinburgh city council before moving into acting; his first TV role was in Rebus in 2001. He has since starred in Line of Duty, Shetland, Dept Q, Guilt, Catastrophe and the film Napoleon, and he is in the first series of Celebrity Traitors. He lives in Hertfordshire with his wife, the actress Lucy Gaskell, and their children, Martha, 14, and Samuel, 10.

When I’m filming I’m up at 5am. Before I’m picked up, I’ll have a cold shower, do my nose spray, trim my nasal hair — all the things the younger me would have laughed at. If I’m home I get up at 6.30am to make my kids’ packed lunches and take my son to school.

I’m a bit boring with breakfast: it’s rolled oats and granola — although when I was filming Celebrity Traitors I rediscovered porridge with honey and salt.

At home I force myself to do some kind of exercise. I did my back in eight years ago picking my daughter up the wrong way, so I’ve gone back to lifting weights, strengthening my core and glutes. I also do a lot of DIY; I’ve a penchant for a power tool.

I still can’t believe I’ve made a career of acting for 30 years. But my family are my life and while it might sound glamorous going away filming, you don’t have them there to share it with. I was in Corfu filming Marble Hall Murders in June, and by the end of two weeks I was looking at videos of the kids as toddlers, gently weeping myself to sleep.

The flipside is that I love my job. I play a lot of compromised, broken men — they’re the most interesting parts. Scott Frank, the creator of Dept Q for Netflix, knows how to put a show together. If the writing is sizzling and you can’t wait to find out what happens next, it doesn’t feel like a chore. I don’t get recognised a lot. Sometimes it’s for Line of Duty and if I’m in Scotland, it’s Guilt. Usually it’s, “Do you work for the council?”

Shetland was ten years of my life. A lot of scenes were in the studio but I went to Shetland every year. It’s magical there. It was a joy to film the 2021 BBC Scotland documentary Meet You at the Hippos with my dad about the sculptures he made for the Scottish New Towns. I’m very proud to be in so many Scottish shows — the landscapes offer a variety of beauty and horror. I prevent any dark characters coming in by mucking about on set. I’ll have a singsong or dance; being silly lets it go.

• Mark Bonnar: ‘I accidentally bought my costume designer’s family home’

It might be toast for lunch — simple fare. I’m a peanut butter fan but it gives me wind, so it contributes to a lot of, “Oh Dad!”

We watch The Traitors as a family, so I knew Lucy and the kids would be excited if I did it. It’s so intense — you have no phone, so all you think about is the show. The line-up was pretty starry. Stephen Fry has been omnipresent in my life — I watched Blackadder growing up — and I loved chatting to Jonathan Ross about Nirvana. It’s mad being in a Traitors WhatsApp group with them all.

I keep in touch with a lot of people after a job. Actors are full of amazing stories. Woody Harrelson and his wife invited me, Lucy and the kids out for dinner when we were filming Last Breath in Malta. We had a smashing night; they’re so lovely. And although Joaquin Phoenix can be shy, by the end of Napoleon we were quite close.

Lucy’s an amazing cook. Martha made an incredible tomato soup at school the other day. If it’s me, it’s beans on toast. Lucy and I met on Chekhov’s The Cherry Orchard, which the Oxford Stage Company was touring more than 21 years ago. We have fun, but honesty and communication are the backbones of our relationship and because she’s an actor too, there’s a shorthand.

I’ve played drums since I was a kid; I was in a band called the Blimps. I’ve got a room at the bottom of the garden where I go to make noise and decompress.

I’m a Liverpool fan, so I watch Match of the Day and play fantasy football when I should be learning lines. I spent the first ten years of my career doing theatre and I still go to bed late. I’m just scared of missing out.
Celebrity Traitors is on BBC1 next month

Words of wisdom

Best advice I was given
I used to be really superstitious, especially before I went on stage, but the actor Jimmy Hazeldine told me superstitions are a load of old bollocks

Advice I’d give
Never lose your sense of wonder

What I wish I’d known
How to lift heavy objects properly