Eoin Colfer is standing in a cinema in Wexford in front of 180 restless primary-school children. Eoin (pronounced Owen) is trying out his one-man show, Fairies, Friends and Flatulence, before this week’s British tour. The 40-year-old author of the Artemis Fowl books is a local hero. Not that he gets much respect. The children at the front treat him with casual familiarity. “Did I teach any of you or your older brothers and sisters?” asks the school teacher turned international bestseller writer to the front rows. “If so, do you’s owe me any homework?”

Colfer may have grey hair but he’s got a naughty ten-year-old’s mentality. Thirty years ago he would have been the kid kicking the back of the seats. On stage he’s like Dave Allen for juniors. Bravely, given the number of Artemis Fowl addicts in the audience, he’s chosen not to mention the eponymous 12-year-old mastermind villain of his novels. Instead Colfer does the whole routine using pictures from his family photo album, projected on screen, for a show that is also going to the Edinburgh Festival.

Nothing more tedious than other people’s snaps, you might think. But with the aid of old Polaroids he has constructed a brilliantly surreal family narrative full of farting, gentle mockery and subversiveness — just the sort of stuff that gives his novels their more-ish readability. At the preview, Finn, his eight-year-old son, was squirming as his father revealed a few bathtime secrets with plenty of visual evidence.

In an hotel in the town Colfer explained the origins of his forthcoming tour. “I started to go on tours with the books a while ago,” he says in a whispering Irish lilt. “The readings got smaller and the storytelling bits got longer. One of my favourite programmes is Have I Got News for You, especially the photograph bit where Paul Merton supplies these mad captions. So it’s kind of like that. I’ve got 50 photos of my family, and the pictures are the punchlines. I generally don’t read from my books at all now. If you see me opening a book, you know it’s not going well.”

Colfer is very much a Wexford man (like his great pal the playwright Bill Roche) and is steeped in the town’s obsession with theatre and opera. “Theatre played a huge part in my childhood. I was in the womb when my mother, a drama teacher, was acting in a farce called The Wild Goose Chase. We were always in plays and light operas. Dad would build the sets for what was enticingly called the Wexford Drama Group.”

Dads he regards as important creatures. “My favourite audience includes a few reluctant fathers. If you can get the dads giggling, everyone relaxes.”

The Colfer clan live around the town. Artemis Fowl is the imaginative by-product of early life as one of five brothers within ten years of each other, all growing up and exchanging insults in a house full of books. Billy, their father, is a retired teacher and local historian published by the Cork University Press.

“It wasn’t until later in life that I realised that writing plays and painting pictures isn’t a normal thing to do. We are all very sharp-tongued. I can be a terrible smart-arse.” So he’s no wild roaring boy, then? “No, once a week I go out with my smart-arse friends for three pints. It’s very sad.”

The fifth Artemis Fowl book, The Lost Colony, is out in September. Thanks to his books, the avid young children he performs to see the Irish legends through his eyes. His is a world in which fairies say “lock and load” and the ancient magic of Eire is blended with weapons-grade hardware and high-level technology.

“I love the old stories and I haven’t cheapened them,” he says. “I was once taken to task at the Celtic Club in Australia, where an irate member turned on me and said: ‘Do you realise your books are ridiculous? There are no female leprechauns.’ But I quickly realised that if I wanted to write in this fairy genre I would have to bring something new to the table. What I brought was James Bond, Men in Black and Star Wars. The first movie proper I ever saw was Thunderball, at a cub-scout weekend.”

Colfer’s success as a novelist guarantees an audience for the show, and the audience is bound to grow when Artemis transfers to the big screen in 2008.

The Hollywood bidding war for the film rights to his first book went on while he was still on duty in the playground at the primary school where he used to teach. Harvey Weinstein has now paired Colfer with a top film director (whose identity is a secret) on a script. Delays have meant that the poor lad chosen to play Artemis is now too old and has been sacked.

Part of what Colfer does on tour is really a theatrical substitute for teaching, which he misses — though not the marking or disciplining. “I taught special-needs children for a year. Children who were at risk or with various psychological problems. One kid would come to school every day and go crazy. My teacher friend who was more experienced said to me: ‘He’s starving.’ We started to feed him up with toast, it was pathetic.”

Colfer now writes in a garden shed with reflective windows so that he can see out but his two boys can’t see in. You wonder why, with all his wealth, he couldn’t do better than a shed. What does an author who has sold eight million books worldwide spend his money on? Trips to Las Vegas? Fast cars? “If I bought a Lamborghini, can you imagine the slagging I’d get here? I couldn’t take it.”

The ribbing will be bad enough when his tour gets to its last date, in Liverpool. The cast of the show are turning up — his brothers, parents and 14 cousins. Will they take their revenge? “Probably. There’s horrendous pictures of them they don’t know I’ve got.”

Eoin Colfer’s tour continues at Manchester Royal Exchange tonight and ends at Liverpool Everyman Playhouse on Saturday