Mackenzie Crook: 'I could play a lead... it would have to be a skinny lead'

Words that spring to mind when one thinks of Mackenzie Crook: "nervy"; "scrawny", or – most unkind – "swivel-eyed" and "lunatic". And yet, within minutes of meeting him, these labels seem harsh and terribly unfair. In person, words like "charming" and "thoughtful" seem apposite, and to these we can now add "author".

Behind the scenes, Crook has been busy writing. Next month, his first children's novel, The Windvale Sprites, written with nine-year-old son Jude in mind, will be published.

"I wrote it as a book that I would have wanted to read when I was a kid, and my son is like a little clone of me; he adored it," Crook says. "In fact, I finished reading it to him last night. "He was so into it. I would've been able to tell if he was just trying to please me."

The story itself, about a fairy that appears after a storm, has been in Crook's head for a long time. "It occurred to me about 25 years ago," he says. "It's all based after the great storm of 1987 – it's been percolating for all that time – and it's only in the past two years that I managed to get it down. It's probably becoming a father that gave me the kick I needed to actually get it done."

So he was more than a little sensitive to his children's reaction when he gave a reading at a book festival earlier this month. "My son was encouraging me because he saw I was nervous, and that was wonderful," he says. Then laughs as he remembers that his daughter, Scout, almost four, was bemused to see her father reading, asking her mother: "Is that really Daddy?" followed by a giant yawn.

He hopes this will be the first of many children's books: that he will use spare time in his acting day productively. "I'm not disciplined when working on something by myself; I don't necessarily get down to it, but hopefully this has turned over a new leaf," he says. "That's my plan, to write more."

In the book Asa, the main character, finds an 18th-century journal, something which Crook would like to write. He also hopes to recount his childhood holidays on his uncle's farm in Zimbabwe: a Gerald Durrell-style book. But Crook doesn't have the confidence to write adult novels: "Maybe I've got more of a child's mind".

He sees writing as an extension of acting, just another way of telling a tale. "While doing this book I came to realise that's what I love doing – it's telling stories, whether writing, drawing, or from acting," he says. "I suppose that's what's in my blood – I'm a storyteller – one way or another."

He started storytelling at a young age, always wanting to be some sort of artist, and was "sort of the best drawer in class" at school. His first jobs were at Pizza Hut and Halfords, where he felt he was "waiting for real life to start".

It finally did when he joined the stand-up circuit, which led to sketch shows and finally the role of jelly-phobic Gareth in Ricky Gervais's The Office. The show has two lasting legacies: Crook's friendships with the cast and the "Gareth hairstyle", memorialised in photos of his wedding to Lindsay: they married just two days after filming ended. "I tried disguising it with products," he says. "But I couldn't hide it really".

Since Gareth, he has been a permanent fixture in the casting director's top 10 for "quirky character roles. "I could play a lead," he says. "But it'd have to be a skinny lead. I think I'm a character actor. I'm happy with the quirky character roles. If lead roles come along, I'd love to do them."

He has been quirky, and indeed swivel-eyed in Pirates of the Caribbean, hanging out with Johnny Depp, whom he admires, but not getting close enough to exchange mobile phone numbers. Surprisingly, he has been quoted ruling out working on any further Pirates instalments, but when I ask him about this he seems concerned he may be doing himself out of work.

"Yeah, I don't think I am, unless they come and ask me then I might," he says. "I would like to say that's done; but the fact is I shouldn't say absolutely never because I had a great time doing those movies; and I'm a big fan of them."

In comparison with the brash Gervais, he has an introverted thoughtfulness. While he's confident in role, whether as an actor or doing stand- up, he's not good showing off in public or down the pub. He looks slightly horrified when I ask whether he's an entertainer in his group of friends.

"I have to do it in a disguised way; I'm not particularly outspoken or the funny one in a group of friends. I don't feel comfortable doing that, so my showing off has to be professional showing off. I enjoy being a different person; acting as a different person is a thrill," he says.

He is much more comfortable in the role of family man: while he was working on Broadway and the other cast members were discovering New York, he was Skypeing his family. "I just left it running all day," he says. "So they'd go off and have their baths, or their tea, and then come and show me a picture they'd drawn or something. There were three months when I was away from my children – it was quite tough."

Away from audiences and the cameras his life is unstarry: he's a keen gardener, and has recently bought some woodland in Essex – "It's the best thing I've done" – where he's encouraging native wildlife. He takes his children there, hoping to instil in them a love for the outdoors.

He has started collecting coins, and seems embarrassed about it. "My dad was a coin collector and he used to try to get me interested when I was a kid, I just couldn't get it: it was really boring. And then something happened a couple of years ago; something flicked in my brain and I was like, 'ahhh, coins'. I just started collecting them and then I looked into the mirror and I was changing to my dad."

His latest big screen appearance is as Ernie, one of the henchman in The Adventures of Tintin, Stephen Spielberg's first 3D film. Crook doesn't seem entirely convinced: "I don't mean to sound old fashioned, but it sounds like a gimmick to me. You still have to wear glasses don't you? Once they get the technology where you don't have to wear glasses, if that's possible, perhaps it won't be."

"You won't recognise me," he says. "They've changed the faces. It has taken three years to get the final results. It seemed crazy, when we were making it, that we weren't going to see the final results for three years."

He loved working with Spielberg, his childhood hero, but was disappointed it wasn't in a more conventional film: "It was frustrating to be in the motion-capture environment.

"It's not like a film set, there are no props, and you're filmed from numerous angles: that information is then fed to the computer, and as long as they get one good take that's all they need, they can choose the angles and close ups later."

He would one day love to work with Spielberg on a traditional film. "It's going to be a great film though," he says, loyally. Right now his day job is in Jez Butterworth's Jerusalem, which has returned to the West End from Broadway. Theatre is comparatively new to him, and, for now, he's enjoying it more than film or television.

"You have to really, really work hard and push yourself and that's a great feeling," he says. The effort saw him lose half a stone off his already slight frame while performing on Broadway. "And I don't have half a stone to spare!"

Nevertheless, he is proud of the work. "It's a very English play; it would have been a shame to have finished it after New York. It needed to come back to home soil. It causes such an amazing reaction in people; they get quite emotional and are blown away."

Crook is unsure what his next project will be, he's in talks about a still-secret project starting in March, and plans to keep writing.

He says he's not particularly ambitious, though, a little predictably, he would like to play more serious roles: "If I can prove myself with some weighty or serious roles, that would be something I would like to explore," He suggests, then qualifies himself, as if concerned he may sound ungrateful: "If it doesn't happen, if I just continue this way, then I have a blessed life. I have no complaints."

One thing is certain: he will not return to The Office for any on-screen reunions. "Despite the continuing US version, he believes the 14 episodes based in Slough was a story which came to a natural end. "It wouldn't have worked if it carried on and on. It'd be foolish to do anymore of that; I can't think how they would do it," he says. "So I'm happy to leave it there. I don't mourn its passing."

Curriculum vitae

1971 Born 29 September, grows up in Dartford, Kent, and spends summer holidays at his uncle's farm in Zimbabwe.

1989 After being turned down three times by the Kent Institute of Art and Design, Crook goes to work at Pizza Hut, Halfords, and a publishing house.

Early 1990s Works alongside Iain Lee as a stand-up, in the role of Charlie Cheese to Lee's Chalk.

1996 Appears in short film The Man who Fell in Love with a Traffic Cone.

1998 Contributor to Channel 4's The Eleven O'Clock Show.

2001 Takes on the role of Gareth Keenan in The Office, receiving two Bafta nominations. Marries Lindsay.

2003–2007 Plays Ragetti in the Pirates of the Caribbean trilogy, alongside film roles in The Merchant of Venice; The Gathering and The Brothers Grimm.

2004 Plays Billy Bibbit onstage in One Flew Over the Cuckoo's Nest, opposite Christian Slater.

2007 Takes West End role of Konstantin in critically acclaimed The Seagull. It transfers to Broadway the following year.

2008 Plays Paul Callow in Brit film Three and Out.

2009 First appears in Jez Butterworth's Jerusalem.

May 2011 Nominated for the Tony Award for Best Featured Actor for role of Ginger in Jerusalem after play transfers to Broadway.

October 2011 Plays Ginger in the final run of Jerusalem at the Royal Court Theatre; he is a henchman in The Adventures of Tintin. Crook's first children's book is published this week.

Genevieve Roberts