The publisher who discovered Harry Potter has said working with Cardiff-born children’s author Roald Dahl helped him see the potential in JK Rowling’s novel.

Barry Cunningham has worked with some of the most well-known children’s authors in the world.

He said Roald Dahl was “a tall, quite grumpy, rather heroic, very frank author” who was adored by children.

“He was occasionally extremely grumpy and short tempered with adults, but never with children,” he told the Books That Made Me programme

on BBC Radio Wales.

Roald Dahl was born on 13 September 1916 in the Llandaff area of the Welsh capital, and died on 23 November 1990, aged 74.

As marketing director for Puffin, Mr Cunningham travelled around the country with him.

It was during one of those marketing trips that Dahl revealed what he believed was the secret to the success of his books.

Mr Cunningham said: “I remember a long drive, which was very difficult because he had hurt his back in the war.

“I said to him, as you do when you’re very young, ‘Mr Dahl, what is the secret of your popularity with children?’

“I just blushed to hear myself say that, and he took it seriously. He said ‘the thing you’ve got to remember Barry, is that humour is delayed fear, laughter is delayed fear.’

“And really, I didn’t understand that at the time, but if you look at the way he uses humour and the way that children use humour, perhaps sometimes it’s the only weapon they have against terrifying circumstances or people. That’s very indicative of his stories and the style of those stories.”

Later, working for Bloomsbury, the first Harry Potter book came across his desk, and he believes his experiences with Dahl helped him see its potential when many other publishers had not.

“I think it was because I didn’t come from a traditional background. I’d come from marketing and promotion. I’d seen how children relate to books, so I perhaps wasn’t looking for those kinds of books that tried to teach them lessons, or tried to be good for them.”

Barry said he still remembered what struck him when reading Harry Potter and the Philosopher’s Stone for the first time.

“I read it overnight and I suppose the beginning did slightly remind me of Roald Dahl, Harry and his cupboard. But the other thing was the bond between the children and the friendship and very, very importantly – and, again, unusual for any kind of fantasy at that time – was the humour,” he said.

“I wouldn’t pretend to you I predicted at that time though that Harry would take over the world, and then have all those adult readers, [that] it would be so important to multi generations. I didn’t predict that.”

JK Rowling has previously said if it was not for Barry Cunningham, Harry Potter “might still be languishing in his cupboard under the stairs”.

“I doubt any of the writers with whom he’s worked, could be more grateful to him,” she added.

Mr Cunningham said he was very touched by her praise.

“It is lovely. I just loved it from the beginning, but of course I didn’t know that every other publisher in the world had already turned it down. So it was lucky that she found me and I was lucky that I found her. I mean, that’s extraordinary, isn’t it?”

In 2000, Mr Cunningham started his own “lively and creative” publishing company, Chicken House, which has a special emphasis on original children’s fiction books.

He remains passionate about discovering new writing talent, but said he would never tire of being known as the man who brought Harry Potter to the world.

Barry Cunningham’s interview on Books That Made Me with Lucy Owen was first broadcast on BBC Radio Wales on Friday at 18.30 BST and is available on BBC Sounds.