Stephen Mangan escaped law for acting — now he wants more time at home

“The ultimate distillation of the crime drama is Scooby-Doo,” he says. “I watch quite a bit of Scooby-Doo, because I’ve got small children, and it’s amazing how little crime series deviate from that formula. It’s all the same plot points – the murder, the false lead, the denouement where the murderer is unmasked and when he explains to the pesky kids why he did it.”

The ten-part series, set in 1901, is based, loosely, on the real-life friendship between Doyle and Harry Houdini, and their shared interest in the supernatural (Doyle, in later life, was an energetic champion of spiritualism; Houdini, the master-illusionist, vigorously opposed any notion of “magic”). Michael Weston (House, Law & Order: SVU and Six Feet Under) makes a wonderfully brash and bumptious Houdini, the ideal counterpart to Doyle/Mangan’s stiff and extravagantly moustachio’d upper lip.

“It’s not a documentary,” Mangan, 47, points out. “Arthur Conan Doyle and Houdini hadn’t met in 1901, they never solved crimes together. I don’t look anything like Doyle and I don’t sound like him – I’m not doing a Scottish accent. He’s a figure with a vast and rabid fan base, who I’m sure will have plenty to say about my Magnum moustache, but I’m fine with that, because the thing’s a fantasy, a kind of Edwardian X-Files.”

Each episode features a plot line with crimes committed, apparently, from beyond the grave or at least with some level of supernatural involvement.

"What’s interesting,” says Mangan, “is that Doyle, the person who believes in spiritualism and life after death, is also a very scientific man, a doctor, whose greatest creation was probably the most rational, sharp-minded intellect ever created in fiction. He’s not some credulous fool.

“Obviously, no one has ever proved scientifically that the supernatural exists, so my character is pretty much on a losing wicket every week. But the script is nicely complex.”

As for Mangan, he is not a “believer”.

"I'm a rationalist. I don't believe in any of it. Can I understand the impulse to believe? Absolutely. I watched both my parents die. I watched my grandfather die, and the desire to believe that that's 'not it' is overwhelming. I remember after my mum died, I’d watch ants crawling across the floor and think, ‘Is that my mum trying to get back to me?’ Which is crazy, why would she come back as an ant? But I totally understand that emotion. I really do.

“I’m prepared to believe that there’s all sort of stuff out there that we have no knowledge of at the moment. But it’s just guessing... The belief in the supernatural diminishes the beauty of life.

“There’s a beautiful medieval image of life, where they have this idea of a bird flapping through the darkness, then it bursts through into a medieval hall which is full of sound and light and flies out through the other end, back into darkness. And I suppose the only bit we know about is that bit in the light. It’s glorious, and it wouldn’t mean anything without a beginning and an end. There’s a delight in that, especially in someone being allowed to live the whole range of that journey. That’s why it’s so tragic when someone dies young. But there’s so much beauty and poetry and magic that actually exists, I don’t feel the need to go looking for it ‘beyond’.”

There’s a great deal of family history bound up in this passionate response. The son of Irish immigrants, Mangan grew up in north London. “My dad worked on the building sites, and my mum was a barmaid in Camden – they couldn’t have been more stereotypical of their time – but then Dad did quite well in his business, and I ended up going to a public school [Haileybury College] and Cambridge.”

Three months after graduating with a law degree, Mangan came home to nurse his mother, Mary, who died of colon cancer at the age of 45. It was a time of intense reflection, and he decided that life was too short not to follow his “background dream” of acting. Rada followed, and a six-year stint in classical theatre, before he made his breakthrough TV appearance in Adrian Mole: the Cappuccino Years in 2001.

There is, he claims, a significant and helpful crossover between law and acting "It's all just stories. When you study law, you come across a lot of stories about people doing bizarre things and your job is to somehow unpack all that stuff and lay it out in a codified way so that you can apply it to other situations."

The 2011 British/American series, Episodes opened the field for work in Hollywood and forged a close friendship between Mangan and his co-star Matt LeBlanc, former Friends star and no co-host of Top Gear.

"If anyone was born to do that show, it's Matt," says Mangan. "He really does know his cars inside out. And he also managed to do the fastest lap in the show’s history, giving a comedy routine as he went round, and being really funny. So it’s the perfect fit.”

Like his character in Episodes – the next series starts filming next month – Mangan is ambivalent about the California lifestyle. “If you go for a meeting with American TV executives and they say you’re amazing, you better say, ‘Yes, I am indeed amazing.’ You better agree with them, otherwise they’re thinking, ‘Why are we talking to you, then?’ It doesn’t sit terribly well with the British temperament, but I’m learning.”

The emotion is ramped in Houdini & Doyle by a plot-line involving Doyle’s dying wife, played by Mangan’s own wife, Louise Delamere.

“Seeing her lying there was pretty upsetting, and it’s pretty peculiar to have to kiss and chat with my actual wife in front of a camera crew. They asked if one of my sons [the couple have two children and a third due this month] would play Doyle’s son, but I said no. It’s weird enough as it is.”

Mangan has signed for a five-year stint with Houdini & Doyle, but he’s also busy with his own production company, commissioning writers and directors “who I know are good and nice to work with”. Birthday, in which Mangan recently starred as a pregnant woman at London’s Royal Court Theatre, was a “home-grown” hit, and there’s a film in post-production with Juno Temple and Timothy Spall.

“I like being farther upstream in the creative process, and I’m keen to arrange things so that I have more time with my family. Love and work. What more do you need?”

Houdini & Doyle is on Sunday 13th March at 10:15pm on ITV