Steve Kilgallon and Michelle Duff.

was turned into a film starring Alex Pettyfer in 2006) for new editions, he says he found little needed to be changed, beyond a couple of outdated gadgets and celebrity references: ‘‘I was quite pleasantly surprised how little work I had to do . . . the books have held up – and that’s the secret of it. Incidentally, it’s also why the books have done so well in so many different countries – it doesn’t just appeal to English boys it appeals to all kids. I always believed in classic storytelling.’’ But yet even for Horowitz, now 60, it’s getting harder and he feels his time as a children’s writer may soon be up: ‘‘Every year you are further away from your audience, and it gets harder to reach out and get into their mindset.’’ He would use his two sons as an inspiration and a touchstone, but Nicholas and Cassian are now 24 and 26 (‘‘and that’s not helpful to me’’) and he’s not impressed by the idea of waiting until their children are old enough to become his

‘That may sound arrogant. But it’s absolutely the truth’

Toad series – he also writes books that deal with serious issues like AIDS, asylum seekers, and more recently, war.

‘‘I’ve always written about what to me are important and sometimes serious topics, but in my earlier books there was a much more obvious surface of humour, or sense of comedy,’’ Gleitzman says.

‘‘While there’s still humour in the books I have written about war, because that’s how I approach writing about young people facing adversity – by giving them a dimension of imagination and optimism – the serious topics are closer to the surface.’’

The Once series is set during the holocaust, with the main character a 10-year-old boy named Felix. The books are among the most special to Gleitzman personally, who himself wondered if it would be possible to strike the right balance between light and dark elements of humanity in the stories. ‘‘Writing about violent and disturbing forms of human behaviour is tricky, because I think it’s important to not betray or belittle what went on and what people actually experienced, but there’s only so much confronting, violent, visceral material that we can read,’’ he says.

‘‘If you write a piece of fiction that has so much stark, upsetting, appalling behaviour that your readers have to close the book and turn away, you’ve failed as a storyteller. That’s not to say you shouldn’t challenge readers. In a perfect world we wouldn’t have to read about violence and cruelty and loss and despair at all, but I think we’re not serving young readers well if we pretend the world is a place where none of these experiences happen.’’

However, setting a story of what is essentially friendship during a mass genocide was always going to be a tough ask.

‘‘I wasn’t sure if I could write about that time and place for young readers or even if I should be trying to. It was a process of several years of research, of thinking, of getting to a point where I could give it a go,’’ Gleitzman says.

‘‘I still wasn’t sure I could make it work but, well, I did, because the book’s published, it sold a lot of copies, it’s been read by young people around the world. And I think because it was challenging, and scary, and ultimately satisfying, it feels like a special one.’’

Gleitzman also explains that he’s spent some ‘‘key years,’’ with the novel’s protagonist, Felix, who is now aged 14. For him, characters become like friends – and that’s who he writes the books for.

‘‘I always imagine I’m writing the story for the main character – that I’ve been given the responsibility of being both their scribe and companion. I brainstorm with the character about the best solutions to their problems, and I’m focused totally on that.

‘‘Indirectly I have my readers in mind but it’s that individual character who I imagine reading the story when it is complete. Although we all like to be generous and think of others, writing works well when it’s a fairly selfish process.’’

Gleitzman is often asked how he manages to connect to young adults. To a certain extent it’s not forgetting what it was like to be a child, he says – but on the other hand, we are all just big kids. ‘‘What young people want is what we all want – to be loved, to be accepted, to make a mark on the world, to live an adventurous and stimulated and fulfilling life.

‘‘Adult culture for a range of reasons seems to diminish and belittle childhood a bit – it’s interesting that we use the world ‘childish’ as a sort of disparaging term,’’ he says.

‘‘Obviously adults have a sexual dimension to their lives which is different to children, and adults have anxieties and neuroses and kids are free of that, but the big themes of life and what every character wants in a story isn’t that different.’’

As he approaches three decades of writing, Gleitzman counts himself lucky he’s never been short of ideas. He’s always got two or three books maturing in his head, and has learnt he doesn’t need to jot his ideas down. If they’re meant to be, they’ll stick.

‘‘I think ideas are sometimes a bit like migratory birds,’’ he says.

‘‘They come and settle on your shoulder and you get all excited and then you realise that, no – I think this particular idea was just having a rest with me, and it’s on its way to another author.’’ Morris Gleitzman is also at the Writers Festival on May 13 and 14.