Philip Pullman, author of the His Dark Materials trilogy, is one of the world's best-known children's writers.
Pullman published his first children's book in 1982
He has won several awards for the trilogy - Northern Lights, The Subtle Knife and The Amber Spyglass - including the Whitbread Book of the Year Award in 2002.
Last year, Northern Lights was made into Hollywood film The Golden Compass, starring Nicole Kidman and Daniel Craig.
Billie Piper played the lead role in the BBC adaptations of his Sally Lockheart novels, The Ruby in the Smoke and The Shadow in the North. Pullman has also written several other books.
Pullman's His Dark Materials books have been controversial with some Christian groups accusing him of using them to promote his atheist beliefs, a claim he has denied.
As a stage adaptation of his 2005 book, The Scarecrow and his Servant, opens at London's Southwark Playhouse, Pullman has answered some of your questions about his work.
HIS DARK MATERIALS
Do you feel that His Dark Materials was your magnum opus and any future work will forever live in its shadow?
Shane O' Flynn, Tallinn, Estonia
I hope not. I've got plenty of other things to write yet.
When/why/how/where did you first get the idea about people having daemons?
James Peacock, Chanthaburi, Thailand
In 1993/because I couldn't get the story going without it/by sitting and thinking/in the shed at the bottom of my garden.
What is dust? Is it a force for good or evil? Does the idea come from mythology or space science?
Donna Iverson, Burlington, US
I'm not going to tell you whether it's good or evil. You have to work that out for yourself. As for where it comes from, it came out of my head.
You hint towards the end of The Amber Spyglass that there is an untold tale of the adventures of Kirjava and Pantalaimon. Do you ever intend to write these adventures?
Richmond Clements, Highlands, UK
There are many things I intend to write. I wish I could think I had the time.
Did you ever expect His Dark Materials to become so popular, as well as such a controversial subject?
Emma, Alresford, UK
I have always wanted to know more about Lyra's parents and I recently heard that a story about how they met could be in The Book of Dust. Is this rumour true?
Sarah Vickers, Ruskington, UK
Well, it hasn't happened yet, but I haven't finished the book yet! You never know what might happen.
Are you still writing The Book of Dust? Can you give us a little more insight about it?
Kim, Charlottesville, US
Not yet. I never show anyone work in progress.
THE GOLDEN COMPASS FILM
What compromises were made to religious sensitivity during the making of the film version of your fabulous story? Do you feel you were in some way censored by the studios?
They were being careful, obviously. But there are so many compromises when you make a big expensive film; everybody who invests work or money into it has a point of view. It's amazing that any films get made at all.
When they made the Golden Compass film, which character did they get just right?
Kirsty Rose, Lancashire, UK
Lee Scoresby. Sam Elliott was everything I'd hoped for.
Do you know if and when The Subtle Knife and The Amber Spyglass will made into films?
Frank Everett, Stevenage, UK
I doubt whether they will now. The film lost so much money in the US that I think the studio will be very careful about making a sequel.
Do you consider it offensive that Christian groups challenge you that your books contain anti-Christian sentiment?
No. I simply think how dull their lives must be, to find something so harmless such a threat.
You are sometimes accused of having an "atheist agenda" in your Dark Materials trilogy. Did you consciously write any part of the stories with an agenda?
Karen Wood, Bourne, UK
I don't take any notice of that sort of criticism. Of course I didn't have an agenda; I write stories, not arguments. But equally, if you believe something strongly, your beliefs are going to influence the way you tell stories, and the kind of stories that come to you to be told.
If The Narnia books are a Christian allegory, could the Scarecrow and his Servant be interpreted as a humanist allegory?
Jo Garton, Swindon, UK
Well, it could be, but I don't know what you'd gain. I didn't intend it as any kind of allegory - I don't like allegory at all - it's just a fairy tale.
Do you think a showdown between secular and religiously-based cultures is inevitable given the apparent rise in religious fundamentalism in the world?
Peter, Cambridge, UK
No. I think the fashion for fundamental ways of thought will fade eventually. Living at a pitch of hysteria is exciting for a while, but then people get tired of stoning martyrs and exorcising devils and being fearful of shadows, and want to live normally again. But if such a clash does come, we shall have to fight hard.
I read the Dark Materials trilogy and actually found it to affirm my own beliefs in God while being critical of church organisation. Is a reader allowed to have a Christian/religious reading of a text that is supposed to be atheistic?
Ian Gilbert, Antwerp, Belgium
Good grief. Where do these ideas come from? "A text that is supposed to be atheistic" - who says it's supposed to be atheistic? Not me. And as for being allowed or not to read it in a supposedly unauthorised way - I am a devout believer in the complete democracy of text. It sounds to me as if you think reading is surrounded by rules and prohibitions and commands. It isn't! Not a bit of it! Once a book is in your hands, ITS INTERPRETATION BELONGS TO YOU. You can read it in any way you like, and take away any meaning that makes sense to you. That's the great freedom of reading.
Of course, if you want to persuade someone else that your reading is a good one, you have to do the usual literary-critical things like finding evidence in the text, like looking for patterns of imagery or influence that support what you claim the book is saying, and so on. But the idea that the author is sternly watching every single reader to make sure that they're reading in the RIGHT WAY belongs to some nightmare of authoritarian mind-control. Reading is a democracy!
How long does it take to get from idea to planning stage, first draft and finished book? How much do you plan beforehand?
Caroline, Dublin, Ireland
It doesn't work like that. The implication of your sequence idea - plan - draft - finished work is that things have to follow that order, but they never do. It's a muddle. But not just a muddle, because it contains seeds of order that gradually flower unexpectedly into structure. That happens all the time, and you can't hope to control it. Planning is for control freaks. No-one ever controlled a novel into existence.
When did you first realise that you were good at writing?
James Angus, Manchester, UK
When I was at school - I suppose when I was about nine or 10. I just found some things easy, as other kids found maths easy.
You've said that you often have no idea where your story is going when you first start it. You must have to go back and re-edit initial chapters multiple times to fit later adaptations. Are there parts of your books that you've axed as part of this process that you rather regret?
Ian Renwick, Hong Kong
No - if anything I regret not having sacrificed more.
Do you write with the intention of appealing to a children's audience or did you discover that your books were accessible to children and, of course, us adults?
Vicki Jacob-Aas, Mariestad, Sweden
Well, you hope that your books will appeal to a large audience, but you can never tell. I like a mixed audience - both adults and children - because the adults keep the children serious, and the children keep the adults civilized.
I just read The Broken Bridge and loved it! I was wondering, how do you write from the point of view of characters that are so different from you (half-Haitian teenage girl)?
Mandi, Arkansas, US
Thank you for your comment. I'm glad you enjoyed the story. As for how I wrote it, it's a matter of imagination. You imagine what it would be like to be someone else, and then you write about it.
What is the best fan letter you have received?
Rachel Hill, London, UK
The first one must have been the best.
Would you consider writing a story for Doctor Who's time and space adventures?
George Swann, London, UK
No. I write the things I want to write, not things someone else asks me to.
As a great lover of William Blake, I am interested to hear when and how you first discovered his work. To what extent has his work influenced your writing?
Randal Jack, Bristol, UK
I first came across his poetry as a teenager. I loved it at once, and I've revered it ever since. I don't know to what extent it's influenced me - completely, I should think.
I loved Billie Piper's portrayal of Sally Lockhart. Do you know whether the final two books in the saga are to be made into films?
Rohan James, Melbourne, Australia
Billie is a delightful actress, and I was very glad to see her as Sally. I don't know whether there are any plans for the remaining two stories.
How important is the Campaign for the Book, and what value do you place on libraries, especially for young people?
Kate Garnett, Guernsey, UK
It's very important. Books should be at the heart of every place of learning, and every community should have a library where children are welcome.