SOME WRITERS are, well, predictable. Even the best of them can get fixed in certain grooves, concentrating on historical stories or romances or thrillers. But screenwriter and novelist Frank Cottrell Boyce is much more difficult to pin down.

The writer behind such diverse films as

24-Hour Party People

and

Tristram Shandy: A Cock and Bull Story

, he was once described by the great film critic Roger Ebert as “arguably the most original and versatile screenwriter in England”. Having worked with everyone from Danny Boyle to Michael Winterbottom, in 2004 he also began writing hugely successful children’s books. His latest unpredictable project is

Chitty Chitty Bang Bang Flies Again,

a sequel to Ian Fleming’s only book for children.

Chitty Chitty Bang Bang Flies Againis a fantastic book, exciting and very funny, with wonderfully odd and creepy villains, but it would never have occurred to Cottrell Boyce to write about the amazing car if he hadn't been asked by Fleming's estate.

Turning down the request wasn’t an option. “I didn’t get any time to think about it,” he laughs. “I mentioned it to my kids and they [immediately] said ‘you’re doing it.’”

Set in the present day, Chitty Chitty Bang Bang Flies Againis the story of the Tooting family, who buy a battered old camper van with a very unusual engine that once belonged to the fabulous flying racing car Chitty Chitty Bang Bang.

Friendly and funny, Cottrell Boyce is fantastic company, especially when the conversation turns to children’s literature. His literary hero is the Finnish author Tove Jansson, best known for her beautiful, strange and funny novels about the troll-like Moomins, which he first read as a child and still loves.

“She really, really spoke to me,” he says. “She was a tiny Finnish lesbian living on an island – all notions of demographics go out the window here, because I’ve never felt such a strong connection with anybody even though she was clearly a million miles away from who I was.” He points out that great children’s literature can be, and often is, more complex and profound than books aimed at adults.

"[The Moomin books] looked like children's books but they weren't, which is the opposite of now, where loads of things are dressed up as Booker Prize winning books that are completely infantile," he says. "The one where Moomin wakes up in the middle of winter [ Moominland Midwinter]makes Kafka look like a cute little Japanese kawaii story."

His other literary idol is also a female children’s writer, E Nesbit. “I came to her late, but it unlocked something in my head. It’s way beyond an influence,” he says. “She’s massively underrated. I love comic writing – I love Damon Runyon and PG Wodehouse and David Sedaris. But none of them are in the same planet as E Nesbit.”

Despite his love of children's literature, it wasn't until director Danny Boyle urged him to turn his script for Millions, the movie they were making together at the time, into a children's book that he found his voice as a young people's novelist. "I had been working on a children's book for years and it was rubbish," he says. "And then Danny said 'Write this one' and I just wrote it in a few weeks. It felt like it came easily, but with a screenplay you write it for years and are always changing it. So [because Millionsstarted as a script] I'd played with the idea for years before I came down to write the book. And I've never found it so easy since."

Married with seven children, Cottrell Boyce grew up in Liverpool. He studied English at Oxford – where he met his wife, Denise – before becoming a critic for Living Marxismmagazine and then a scriptwriter for Coronation Streetand Brookside. He made a name as a serious screenwriter with his collaborations with the director Michael Winterbottom; after their first film, Butterfly Kiss,they worked on everything from Bosnian war drama Welcome to Sarajevoand dark western The Claimto 24-Hour Party People,which told the story of Manchester's Factory Records, and T ristram Shandy: A Cock and Bull Story.

It's an eclectic filmography, but Cottrell Boyce says Winterbottom was the one driving the jumps from one subject and setting to another. "We'd be making The Claimin the Rocky Mountains and he'd immediately want to do something about where he came from, so we'd then do 24 Hour Party People.And he'd no sooner set up shop in Manchester than he'd want to make a film in Shanghai."

The director and writer have since had what Cottrell Boyce now mildly describes as "a bit of a falling out", and he took his name off their last collaboration, 2005's Tristram Shandy,asking to be credited as 'Martin Hardy'.

"It was nominated for a script award and so was Millions, so I was double nominated but under different names," he says. "And not everybody knew." He laughs. "So when Millionswon I got up and made a fantastically generous speech about T ristram Shandy . . ."

He's now working on two more books about Chitty, but Cottrell Boyce hasn't abandoned the big screen. The Railway Man, his adaptation of Eric Lomax's memoir of life in a Japanese POW camp during the second World War, is currently in production, with Colin Firth signed on to play the lead. But much as he enjoys screenwriting, he prefers the feedback he gets from his younger audiences.

“I love reading to kids,” he says. “It’s fantastic. I find it really exhausting but I love it. You go to film festivals and people just come up and say ‘I love your work.’ Whereas when you talk to kids, they’re very alive and they’re asking questions. The book is recreated anew every time you read to them. Some people say ‘I write for me.’ But I’m definitely writing for the moment I stand up [in front of a group of children] and think: ‘Oh, I must make sure there are no boring bits.’ I don’t want to plough through anything too complicated. I want it to work.”

Classics in the making

“The time will soon come when Frank Cottrell Boyce’s children’s titles have passed into the canon of the classics,” wrote author Philip Ardagh in 2005, and those books are just as varied as his films.

His first book, Millions, the story of two brothers who find over £200,000 in cash just before Britain changes to the euro (well, it was written in 2004), won the prestigious Carnegie Medal.

He then wrote Framed(2005), in which the world's most valuable paintings are taken to a Welsh village for safe keeping and one girl decides an art heist will save her family's struggling business – it was turned into a BBC drama.

In 2008's Cosmic, a boy who looks old for his age poses as his friend's dad so they can both go on a trip to space station.

Chitty Chitty Bang Bang Flies Again is published by Macmillan Children’s Books, £9.99