Sam McBratney guesses why his Guess How Much I Love You has sold 30 million copies

I regard myself as a journeyman writer who has been in the business of writing books, short stories and radio scripts for more than 40 years.

There is considerable interest at present in a picture book of mine published in 1994. Twenty years on, Guess How Much I Love You has achieved sales of some 30 million copies. It's a story about Little Nutbrown Hare and Big Nutbrown Hare, who now speak to one another in 53 of the world's languages.

Guess How Much I Love You is an enigma. It is not just your ordinary bestseller; it is a repeating bestseller, more than a million copies a year for 20 years. It's difficult to explain why a story about two hares in a field should do so well. There was no connection with a movie or a TV series. It began as a word-of-mouth, hand-selling phenomenon approved by independents and book chains alike, and went from there.

Where did the idea come from?

Often, a writer will know the moment of a book’s origin and can faithfully describe it. For example, quite a few years ago Michael O’Brien of the O’Brien Press said to me (knowing that I live overlooking Lough Neagh), “Sam, everybody’s heard of the Lough Ness Monster. What about Lough Neagh….?” – a conversation which led to the story of how Noblett, a placid and retiring soul, meets his more theatrical celebrity cousin, Nessie.

Guess is different. I don't know where it came from. It's an idea that finally surfaced after an editor at Walker Books suggested that I write a picture book, a story for a Big One to read to a Little One.

I remember that in tackling this genre, I was determined to write something that children would not tire of hearing – and, just as important – something that parents would not tire of telling. Instead of making bedtime reading a chore for the grown-ups, make it a celebration.

I remember, too, that I set out to capture with a light touch a moment of tenderness between a parent and child.

Why did it succeed?

Like other writers, I have a list of what I call “dead ducks” – books now remaindered which will never be heard of again. Out of print. Other books do quite well and a few keep ticking over: but why should a story about two hares in a field be the one to command such sales?

I don’t know, but I can offer a few guesses.

I suggest first, Anita Jeram’s inspired drawings. They are not “bunnies” – they manifest the awkward boniness of hares in the wild and the choreography is superbly managed (there is a lot of movement in the story.)

Secondly, the design/presentation of the book is a delight. For example, the hares wear no clothes (compare with Peter Rabbit and most other picture books with animal heroes.) The setting is kept so natural and timeless that the story might have been written 300 years ago. That sense of timelessness comes from the design team, not me.

Thirdly, there must have been shrewd marketing decisions going on in the background.

And finally, after the drawings and the design and the marketing – in the beginning were the words. Take the beloved child onto your knee, read him or her this story two or three times and you might agree with the parent who wrote to me saying “Somehow you get the feeling that this story is just ... true.”