Barry Loser is no loser. In fact, Barry Loser has just won his creator, Jim Smith, one of the most prestigious prizes for children’s literature.

The 2013 Roald Dahl Funny Prize was awarded to Smith for I Am Still Not a Loser, the second instalment in his series about Barry, who, despite his unfortunate surname, is convinced that he is the “keelest person that has ever lived” - “keel” being a cooler way of saying “cool”.

The book, which was recognised in the 7-14 age category, includes enough poo, fart and bogey jokes to keep any child happy, and lots of paragraphs ending with “Amen”. Amen.

In recent years, the Funny Prize has recognised the talents of, among others, Jamie Thomson for Dark Lord: The Teenage Years, Liz Pichon for The Brilliant World of Tom Gates and Louise Rennison for Withering Tights.

Smith, an illustrator credited only by the big-nosed Barry Loser for putting the commas in the book, has long enjoyed writing for children but did not believe he could earn a living that way. “I had always written little stories but they were unsellable and weird,” he tells TES.

But after losing his job as a designer for a chain of coffee shops, he decided to take his weird stories a bit more seriously. “I was going around publishers and someone told me: `Your sense of humour works really well for eight-year-old boys.’ I thought, OK, I will now write a proper kids’ book.”

So, at the age of 38 and with his first child on the way, Smith created schoolboy Barry Nothing, whose surname was swiftly changed when his agent suggested Loser.

After the first book, I Am Not a Loser, came I Am Still Not a Loser and I Am So Over Being a Loser. Part four in the series, I Am Sort of a Loser, is due out later this month.

A special short edition, I Am Nit a Loser, which features creepy-crawlies, will be released for World Book Day on 6 March and two free e-books, My Mum is a Loser and My Dad is a Loser, are also available.

Smith was brought up in Twickenham, south-west London, the second of three children. “When I was a kid, I knew I wanted to sit at a desk and make things,” he says.

“In primary school I drew Christmas posters and leaflets. I just really enjoyed school. I was always in a kind of competition with my best friend about who was the best drawer. He was more realistic, I was more cartoony.”

It wasn’t fine art but design that obsessed Smith as he grew up in the 1980s, an era when advertising - the industry in which his father worked - was epitomised by shiny creative, big business and big budgets.

“I loved American stuff,” Smith says. “I read Mad magazine. I collected Coke cans - this was when I was 12. People would bring them back from holidays for me; I’d write to Coca-Cola and they’d send me things like stickers.”

Barry, the champion of the world

A lot of the stories in the Barry Loser books are based on his days at secondary school, Smith says: “All that stuff about those feelings of falling out with your friends and then going off with other friends, then trying to be cool to fit in with the new gang.”

After leaving school, he completed an art foundation course at Wimbledon School of Art and went on to study for a degree in advertising, graphic design and illustration at Buckingham College (now Buckinghamshire New University). He dreamed of illustrating for The New Yorker magazine.

But after making a life-size wooden cut-out of Santa Claus for his father’s shop - who by then had left advertising and gone into lighting - he was contacted by the owners of Puccino’s coffee shops, who had a store a few doors down, and he ended up drawing their artwork for the next 10 years.

His sense of humour sometimes got him into trouble. A tea-bag tag that featured a drawing of a man hanging by the neck was banned, and a cup bearing the slogan “Neither hungry nor homeless” was also scrapped.

Smith also set up the Waldo Pancake card and gifts label, for which he produces items such as an eye mask that declares itself a “useless superhero mask” and a lunch box with “suitcase for a really short holiday” printed on it - just the kind of silly humour that appeals to children, whether they are 8 or 38.

The Barry Loser books have proved a hit, with the translation rights sold to 12 countries, but winning the Roald Dahl Funny Prize - set up in 2008 by former Children’s Laureate Michael Rosen in celebration of books that make children laugh - was Smith’s keelest moment yet.

“It was brilliant to win,” he says. “I was expecting to hear someone else’s name read out, so I was very shocked when it was mine. I had to squeeze past all these people to get to Michael Rosen. He said some really kind things.”

Joining Smith on the winners’ podium was Simon Rickerty, whose book Monkey Nut was named the funniest title for children aged 6 and under.

Rosen praised I Am Still Not a Loser, saying: “The mix of words and drawings are a playful reminder of everyone’s home-grown cartoons, and the big nose motif has become a cult.”

But success seems unlikely to go to Smith’s head: celebrations at home were limited to a Chinese takeaway with his wife, although it was a “really nice one”.

And now it is back to reality. Smith and his wife, a freelance editor and writer, share an office in their house; it appears very grown-up at first glance, but on closer inspection the influence of the eight-year-old boy can be seen. Here are some Coca-Cola cans; there is a pencil pot in the shape of 1980s TV creation Alf. And then there is Smith’s winningly silly book. Amen.

Mind the hoverpoo!

An extract from Jim Smith’s I Am Still Not a Loser:

“You know when someone’s horrible to you in a dream and you wake up really annoyed with them? That’s what happened to me with my best friend Bunky.

In the dream I was my favourite TV character, Future Ratboy, and Bunky was his annoying sidekick Not Bird. We were in the mayor’s office, which looked exactly like my granny’s house.

`You’re the only ones who can save us from the hoverpoos!’ said the mayor, who was played by my teacher, Mr Hodgepodge.

Hoverpoos were the invention of Professor Smugly, who in the dream was Gordon Smugly from our class at school. Gordon Smugly has the most perfect name for himself ever in the history of having a name, because he looks like a Gordon and is smug and ugly.

Professor Smugly had given all the dogs in town his hoverpoo potion so that now, instead of their poos landing splat on the ground, they hovered ten centimetres above it.”