First of all how does it feel to have won the Waterstones children's book prize?
Absolutely wonderful! I am still shocked, and expecting every morning to wake up and find it was all a very life-like and detailed dream.
Where did the idea for Rooftoppers come from?
I was climbing on the rooftop of an Oxford college, a few years ago, and I saw an old beer bottle (I think someone repairing the tiles had probably left it there) and I thought – wouldn't it be fantastic if people did actually live up here, on rooftops, and nobody knows because nobody ever looked hard enough? Do you know if a Victorian ship actually did sink and if so where can we read about the disaster?
Lots of ships did sink in the years around the end of the 19th century, which is when the book is set, often because they caught fire or ran aground – for example, the wonderfully-named steamer Ugie sank in March 1900 when it crashed into another ship – but the ship in Rooftoppers is fictional.
Do you know Paris well and did you have to spend a lot of time there when you were writing the book?
I know Paris quite well, and love it hugely – it's one of my favourite cities – but most of the writing of the book was done in the very early mornings in my study in Oxford, with my feet wrapped up in blankets, before anyone else was awake.
Do you have any evidence that homeless children really do live on the rooftops in Paris and if so I wonder what happens to them when they get too old to do all that climbing?
Alas the rooftoppers are entirely made up! The closest thing to them are the gangs of young men and women who do "parkour" in Paris, which is roof-running mixed with acrobatics.
Has your book been translated into French and if so is it as popular as it is in this country?
It is being translated into French at the moment, but isn't yet out - I've read the manuscript and it's lovely to read it in its "home" language! In French it's called Le Ciel Nous Appartient, which means "the sky is ours".
Is music important in your life and do you play a musical instrument?
I think music is one of the largest and most unwieldy joys there is, and I listen to music every day while I work – mostly jazz and blues. I don't play a musical instrument – my big brother is a professional percussionist and I think he got all the musical genes!
Charles broke lots of rules to help Sophie find her mother Do you think it is OK for grown ups to break rules?
Definitely! – as long as they break the right ones. Not all rules are sensible – it's just a question of making sure your rule-breaking won't hurt anyone.
I think that Charles is the sort of person any child would like for a guardian. Is his character based on someone you know?
Yes! He's based on a mixture of people who I know – both men and women – and also he's my idea of an ideal person. Sometimes people write to ask if he is real and, if so, can they have his phone number – but if he was real I would have married him immediately.
When did you know that you wanted to be a writer and did you consider any other careers?
I can't remember a time when I didn't want to be a writer, but I also wanted to be many other things along the way – an explorer, a tightrope walker, and, when I was very young, the person who arranges those enormous bunches of flowers in Fortnum and Mason.
Can you remember your favourite book from when you were my age? (I am 10 years-old and my two favourites are Rooftoppers and My name is Mina by David Almond)
I am so delighted that Rooftoppers is one of your favourites – thank you! There were lots – there were so many fantastic books for 10-year-olds when I was young, and there are even more now. I loved Matilda by Roald Dahl, and Charmed Life by Diana Wynne Jones, and Ballet Shoes by Noel Streatfield, and Just William and lots of Jacqueline Wilson…
Which other writers do you most admire now?
I admire Philip Pullman very much, because the world he invented in the Northern Lights trilogy feels so real that you can almost touch it.
Which six books would you take to a desert island?
I'd take all of Shakespeare, and all the poems of the poet John Donne – they are fantastically beautiful, and full of wit and hope – and Emma by Jane Austen, which is my favourite adults' book – and I'd take my copy of What Katy Did, because my mother gave it to me when I was eight and I have loved it ever since – and Journey to the River Sea by Eva Ibbotson, and a book on how to survive a desert island, so that I didn't die before I could read my books.
Can you give us a little hint about the subject of your next book – I can't wait to read it?
It's about a girl who drives a sled pulled by wolves across Russia, in the snow, towards St Petersburg. She has a tiny, vulnerable wolf-cub that she has to look after, and she meets difficult and unpredictable people on the way. It's going to be called The Wolf Wilder – I will keep my fingers crossed you enjoy it when it comes out!