Terry Denton & Andy Griffiths: 'I'm far more likely to apologise to Andy than he is to me - but that's only because I need to...'

Andy Griffiths, 53

A children's author, Griffiths (right in picture) has written almost 30 books, including 'Zombie Bums from Uranus'. His bestseller 'The 13-Storey Treehouse' and its sequel, 'The 26-Story Treehouse', have sold more than 360,000 copies in Australia. He lives in Melbourne with his wife and two children

Terry was assigned [as an illustrator] to my very first book in 1993, Swinging on the Clothesline. It was aimed at teachers trying to engage children to read and write; I used to be a teacher myself. My publisher wanted Terry to illustrate it because he had such a good sense of humour, and they knew that his pictures, which were so full of energy and fun, would help bring the book to life.

I confessed to him I'd always wanted to write children's fiction but that my humour was too left of centre; no publisher would give me the chance. He was already a successful illustrator by then, so he said that if I told publishers that Terry Denton would illustrate all my books, I'd get published. He was right. We've collaborated on almost 30 titles now.

We've been lucky: our books have always been popular with children. But there was something about The 13-Storey Treehouse that seemed to connect with children and adults alike. It's basically about me and Terry in our treehouse, trying to write this book and getting distracted along the way. It's pretty zany and wacky but somehow it became a huge success, the bestselling book in Australia last year, and now it's taking off around the world. It's surreal, to be honest.

We're very different characters, me and Terry. Terry works completely intuitively, in a free, associative way. He sits down at his desk and stuff comes pouring out… eventually. I'm not like that. I need structure, I need to plan everything out; I work to deadline. I'm more angsty and bossy. It definitely makes the working environment a bit tense, but he always comes through in the end – even if it is closer to deadline than I would like.

A couple of years ago, we started going away to write in a secluded beach house in a national park in Victoria [in the south-east of Australia]. We work non-stop, 12 hours a day, and by nine at night we're exhausted, ready to unwind. We like the same humour, so we watch Monty Python DVDs, The Fast Show; we're big fans of British comedy.

We don't talk that much; not a lot between us has to be said out loud, but I know where at least some of his skeletons are buried…

Literary success is a strange thing, though I don't think it affects us adversely. I'm actually planning a Treehouse book where a film gets made out of the books, and the fame goes to our heads. It will merely be an exaggeration of our real life, not a reflection of it… I hope.

Writing for kids is hard, because reading is hard. We try to engage kids quickly, give them fewer words and more pictures. Mostly I try to work out how to say something as succinctly as possibly, and let Terry do the rest. Kids love his pictures. I love his pictures.

Terry Denton, 55

Denton has been an illustrator of children's fiction for three decades. He lives just outside Melbourne with his wife and three children

I grew up in awe of the illustrations of [the satirical cartoonist and St Trinian's creator] Ronald Searle, and I was always smitten by Charles Schulz's "Peanuts". I loved Charlie Brown. I'd been working in illustration for maybe a decade when I was introduced to Andy. I guess I was probably always on the look-out for someone I could collaborate with on a bunch of books, rather than just doing a series of one-offs. With Andy, I pretty much found that guy. We laughed at the same things.

We've been working together ever since, and it's always gone well, but never as well as it's going now. The 13-Storey Treehouse has been a freak success – kids, adults, Australia, abroad. I'm amazed, frankly.

It's given us a lot of confidence in what we do, but there is still always compromise in collaboration. I'm far more likely to apologise to Andy than he is to me – but that's only because I need to. The way we work is totally different. Terry is very focused, full of structure. When we go away for our week's writing, he sits at the table all day, puts all our ideas on a storyboard and sees how to make it work. It's all very painstaking and disciplined. I only sit at my desk at the last minute, when deadline is looming, and that's the point at which it comes together for me. I don't do it on purpose, to annoy him; that's just how I am.

We hang out a bit – we go to comedy festivals, occasionally we go for walks in the bush – but I wouldn't say we are particularly close. We live on different sides of Melbourne, for a start. If I'm totally honest – and I'm not sure quite how honest I should be here – I think I find Andy a very intense person. Me, I'm a fairly relaxed guy. It works professionally for us – our working relationship is great – but I think he would be a little too much for me on a day-to-day basis. I need to be surrounded by more relaxed people. Andy isn't the kind of person I would get drunk with and confess everything to, and he wouldn't do that with me, either. We have other friends for that.

He is definitely enjoying the fame this book is bringing us far more than me. But then, you know, I'm older than him, and the clock ticks, right? I don't want to spend my time in front of people talking about the books; I want to spend that time working on the next one, or else with my family. I try to avoid talking pretty much most of the time, to be honest. That's why Andy is going off to promote the book in England and America later this year on his own, without me. I'll be staying at home. I'm happy about that. I'm sure he is, too.

'The 13-Storey Treehouse' by Andy Griffiths and Terry Denton is out in paperback now (£5.99, Macmillan Children's)