Harry Potter: Publisher inspired by working with Roald Dahl

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.”